Stages of Rectal Cancer
Stage I Rectal Cancer
Overview
Following surgical removal of rectal cancer, the cancer is referred to as Stage I rectal cancer if the final pathology report shows that the cancer is confined to the lining or muscle of the rectum. Stage I cancer does not penetrate the wall of the rectum into the abdominal cavity, does not involve any adjacent organs, has not spread to any of the local lymph nodes and cannot be detected in other locations in the body.
A variety of factors ultimately influence a patient’s decision to receive treatment of cancer. The purpose of receiving cancer treatment may be to improve symptoms through local control of the cancer, increase a patient’s chance of cure, or prolong a patient’s survival. The potential benefits of receiving cancer treatment must be carefully balanced with the potential risks of receiving cancer treatment.
The following is a general overview of the treatment of Stage I rectal cancer. Circumstances unique to your situation and prognostic factors of your cancer may ultimately influence how these general treatment principles are applied. The information on this Web site is intended to help educate you about your treatment options and to facilitate a mutual or shared decision-making process with your treating cancer physician.
Most new treatments are developed in clinical trials. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. The development of more-effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Clinical trials are available for most stages of cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. In order to receive optimal treatment of cancer, it is important to stay informed and follow the cancer news in order to learn about new treatments and the results of clinical trials.
Surgical treatment
Stage I adenocarcinoma of the rectum is relatively uncommon and is usually curable by surgical removal of the cancer. Different types of surgery may be recommended depending on the location and specific characteristics of the cancer.
Low anterior or abdominoperineal resection: A low anterior resection (LAR) involves an incision across the abdomen and removal of the cancerous part of the rectum along with some surrounding tissue and lymph nodes. This is often done for cancers that are in the upper part of the rectum. Lower cancers may be treated with removal of the rectum along with extensive removal of surrounding tissues (total mesorectal excision). Depending on where the cancer was and how much of the rectum was removed, the colon may be reconnected to the remaining part of the rectum or to the anus. When possible, the surgery will allow a patient to continue to pass waste through the anus. Some patients, however, may require a temporary or permanent colostomy (an artificial opening that allows waste to pass from the colon to the outside of the body).
If the cancer is very low in the rectum (near the anus), a patient may need to have an abdominoperineal resection (APR). This involves an incision in the abdomen and an incision around the anus. Because both the rectum and the anus are removed, an APR requires a permanent colostomy.
Trans-anal resection or trans-anal endoscopic microsurgery: In some cases it may be possible to remove the cancer through the anus without making an incision in the abdomen. Techniques for removing the cancer in this way include trans-anal resection and trans-anal endoscopic microsurgery (TEM). The operations involve cutting through all layers of the rectum to remove invasive cancer as well as some surrounding normal rectal tissue. This procedure can be used to remove some Stage I rectal cancers that are relatively small and not too far from the anus. If the cancer is found to have certain high-risk features, more extensive surgery may be recommended. These local treatments of rectal cancer offer the advantage of quicker recovery after surgery, but may be linked with a higher risk of cancer recurrence than more extensive types of surgery.1
Strategies to improve treatment
The progress that has been made in the treatment of rectal cancer has resulted from improved surgical techniques and the development of adjuvant treatments in patients with more advanced stages of cancer and participation in clinical trials. Future progress in the treatment of rectal cancer will result from continued participation in appropriate clinical trials.
Improvement in staging: A small fraction of patients with Stage I rectal cancer will relapse following surgery. This is thought to be due to inadequate staging with failure of ultrasound to detect nodal metastases. Other factors, such as how the cancer looks under the microscope, may also have an impact on survival. Patients with poorly differentiated tumors (tumors with more abnormal-looking cells), and those with vascular invasion may have an increased risk of relapse, especially after local trans-anal incision.2 Future studies may help better identify patients who need adjuvant therapy.
Improvements in surgery: Laparoscopic surgery is used for many types of surgery with the short-term advantages of less pain, fewer wound complications, quicker post-operative recovery, and shorter hospital stays. Instead of making one long incision in the abdomen, the surgeon makes several smaller incisions. Special long instruments are inserted through these incisions to remove part of the rectum and lymph nodes. One of the instruments has a small video camera on the end, which allows the surgeon to see inside the abdomen. Once the diseased part of the rectum has been freed, one of the incisions is made larger to allow for its removal.
Laparoscopic-assisted surgery appears to be about as likely to be curative as the standard approach for earlier-stage cancers.3 However, there is still limited information from randomized trials about the approach. In addition, laparoscopic surgery requires special expertise and patients need to be treated by a skilled surgeon who has done a lot of these operations.
References:
1 Nash GM, Weiser MR, Guillem JG et al. Long-term survival after transanal excision of T1 rectal cancer. Diseases of the Colon & Rectum. 2009;52:577-82.
2 Willett CG, Compton CC, Shillito PC, et al. Selection factors for local excision or abdominoperineal resection in early stage rectal cancer. Cancer 1994;73:2716-2720.
3 Jayne DG, Thorpe HC, Copeland J et al. Five-year follow-up of the Medical Research Council CLASICC trial of laparoscopically assisted versus open surgery for colorectal cancer. British Journal of Surgery. 2010;97:1638-45.
Stage II Rectal Cancer
Overview
Following surgical removal of rectal cancer, the cancer is referred to as Stage II rectal cancer if the final pathology report shows that the cancer has penetrated the wall of the rectum, but does not invade any of the local lymph nodes and cannot be detected in other locations in the body.
A variety of factors ultimately influence a patient’s decision to receive treatment of cancer. The purpose of receiving cancer treatment may be to improve symptoms through local control of the cancer, increase a patient’s chance of cure, or prolong a patient’s survival. The potential benefits of receiving cancer treatment must be carefully balanced with the potential risks of receiving cancer treatment.
The following is a general overview of the treatment of Stage II rectal cancer. Circumstances unique to your situation and prognostic factors of your cancer may ultimately influence how these general treatment principles are applied. The information on this Web site is intended to help educate you about your treatment options and to facilitate a mutual or shared decision-making process with your treating cancer physician.
Most new treatments are developed in clinical trials. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Clinical trials are available for most stages of cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. To ensure that you are receiving the optimal treatment of your cancer, it is important to stay informed and follow the cancer news in order to learn about new treatments and the results of clinical trials.
Neoadjuvant therapy
Neoadjuvant therapy refers to treatment given prior to surgery. Many patients with Stage II rectal cancer receive neoadjuvant chemotherapy and radiation therapy; the goals are to reduce the risk of cancer recurrence and to shrink the cancer prior to surgery. If patients are in poor health and unable to tolerate chemotherapy and/or radiation therapy, surgery may be the initial treatment.
Surgical treatment
The standard surgical procedures used to remove Stage II rectal cancer include low anterior resection (LAR) or an abdominoperineal resection (APR). The choice of operation depends on the location of the rectal cancer.
An LAR involves an incision across the abdomen and removal of the cancerous part of the rectum along with some surrounding tissue and lymph nodes. This is often done for cancers that are in the upper part of the rectum. Lower cancers may be treated with removal of the rectum along with extensive removal of surrounding tissues (total mesorectal excision). Depending on where the cancer was and how much of the rectum was removed, the colon may be reconnected to the remaining part of the rectum or to the anus. When possible, the surgery will allow a patient to continue to pass waste through the anus. Some patients, however, may require a temporary or permanent colostomy (an artificial opening that allows waste to pass from the colon to the outside of the body).
If the cancer is very low in the rectum (near the anus), a patient may need to have an abdominoperineal resection (APR). This involves an incision in the abdomen and an incision around the anus. Because both the rectum and the anus are removed, an APR requires a permanent colostomy.
Adjuvant therapy
The goal of providing additional treatment after surgery (adjuvant therapy) is to reduce the risk of cancer recurrence by eliminating any remaining cancer. For patients who received neoadjuvant (before-surgery) chemotherapy and radiation therapy, additional chemotherapy is often given after surgery. If patients did not receive neoadjuvant therapy, they may be treated with both chemotherapy and radiation therapy after surgery.
Strategies to improve treatment
The progress that has been made in the treatment of rectal cancer has resulted from improved surgical techniques, the development of adjuvant and neoadjuvant chemotherapy and radiation therapy treatments, and participation in clinical trials. Future progress in the treatment of rectal cancer will result from continued participation in appropriate clinical trials. Currently, there are several areas of active exploration aimed at improving the treatment of Stage II rectal cancer.
New Adjuvant Chemotherapy Regimens: Several new chemotherapy drugs show promising activity for the treatment of advanced or recurrent rectal cancer. Development of new multi-drug chemotherapy treatment regimens that incorporate new or additional anti-cancer therapies for use as neoadjuvant and/or adjuvant treatment is an active area of clinical research.
Laparoscopic surgery: Laparoscopic surgery is used for many types of surgery with the short-term advantages of less pain, fewer wound complications, quicker post-operative recovery, and shorter hospital stays. Instead of making one long incision in the abdomen, the surgeon makes several smaller incisions. Special long instruments are inserted through these incisions to remove part of the rectum and lymph nodes. One of the instruments has a small video camera on the end, which allows the surgeon to see inside the abdomen. Once the diseased part of the rectum has been freed, one of the incisions is made larger to allow for its removal.
Laparoscopic-assisted surgery appears to be about as likely to be curative as the standard approach for earlier-stage cancers.1 However, there is still limited information from randomized trials about the approach. In addition, laparoscopic surgery requires special expertise and patients need to be treated by a skilled surgeon who has done a lot of these operations.
Improved Approaches to Radiation Therapy: As the technology for radiation therapy has evolved, important advances have been made in the ability of physicians to precisely target the area of the cancer. The goal is to deliver effective doses of radiation to the cancer while sparing healthy tissue to the extent possible. One newer approach to delivering radiation therapy is intensity modulated radiation therapy (IMRT). IMRT starts with a three-dimensional image of the cancer, and allows physicians to deliver different doses of radiation to different areas. The potential advantages for patients include both better tumor control and fewer side effects.
Targeted Therapies: Targeted therapies are anticancer drugs that interfere with specific pathways involved in cancer cell growth or survival. Some targeted therapies block growth signals from reaching cancer cells; others reduce the blood supply to cancer cells; and still others stimulate the immune system to recognize and attack the cancer cell. Depending on the specific “target”, targeted therapies may slow cancer cell growth or increase cancer cell death. Targeted therapies may be used in combination with other cancer treatments such as conventional chemotherapy. Targeted therapies that have shown a benefit for selected patients with advanced rectal cancer include Avastin® (bevacizumab), Erbitux® (cetuximab), and Vectibix® (panitumumab).
Managing Side Effects: Techniques designed to prevent or control the side effects of cancer and its treatments are called supportive care. Side effects not only cause patients discomfort, but also may prevent the delivery of therapy at its planned dose and schedule. In order to achieve optimal outcomes from treatment and improve quality of life, it is imperative that treatment is delivered as planned and that side effects resulting from cancer and its treatment are appropriately managed.
Reference:
1 Jayne DG, Thorpe HC, Copeland J et al. Five-year follow-up of the Medical Research Council CLASICC trial of laparoscopically assisted versus open surgery for colorectal cancer. British Journal of Surgery. 2010;97:1638-45.
Stage III Rectal Cancer
Overview
Following surgical removal of rectal cancer, the cancer is referred to as Stage III rectal cancer if the final pathology report shows that the cancer has invaded any of the local lymph nodes, but cannot be detected in other locations in the body.
A variety of factors ultimately influence a patient’s decision to receive treatment of cancer. The purpose of receiving cancer treatment may be to improve symptoms through local control of the cancer, increase a patient’s chance of cure, or prolong a patient’s survival. The potential benefits of receiving cancer treatment must be carefully balanced with the potential risks of receiving cancer treatment.
The following is a general overview of the treatment of Stage III rectal cancer. Circumstances unique to your situation and prognostic factors of your cancer may ultimately influence how these general treatment principles are applied. The information on this Web site is intended to help educate you about your treatment options and to facilitate a mutual or shared decision-making process with your treating cancer physician.
Most new treatments are developed in clinical trials. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Clinical trials are available for most stages of cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. To ensure that you are receiving the optimal treatment of your cancer, it is important to stay informed and follow the cancer news in order to learn about new treatments and the results of clinical trials.
Neoadjuvant therapy
Neoadjuvant therapy refers to treatment given prior to surgery. Many patients with Stage III rectal cancer receive neoadjuvant chemotherapy and radiation therapy; the goals are to reduce the risk of cancer recurrence and to shrink the cancer prior to surgery. If patients are in poor health and unable to tolerate chemotherapy and/or radiation therapy, surgery may be the initial treatment.
Surgical treatment
The standard surgical procedures used to remove Stage III rectal cancer include low anterior resection (LAR) or abdominoperineal resection (APR). The choice of operation depends on the location of the rectal cancer.
An LAR involves an incision across the abdomen and removal of the cancerous part of the rectum along with some surrounding tissue and lymph nodes. This is often done for cancers that are in the upper part of the rectum. Lower cancers may be treated with removal of the rectum along with extensive removal of surrounding tissues (total mesorectal excision). Depending on where the cancer was and how much of the rectum was removed, the colon may be reconnected to the remaining part of the rectum or to the anus. When possible, the surgery will allow a patient to continue to pass waste through the anus. Some patients, however, may require a temporary or permanent colostomy (an artificial opening that allows waste to pass from the colon to the outside of the body).
If the cancer is very low in the rectum (near the anus), a patient may need to have an abdominoperineal resection (APR). This involves an incision in the abdomen and an incision around the anus. Because both the rectum and the anus are removed, an APR requires a permanent colostomy.
Adjuvant therapy
The goal of providing additional treatment after surgery (adjuvant therapy) is to reduce the risk of cancer recurrence by eliminating any remaining cancer. For patients who received neoadjuvant (before-surgery) chemotherapy and radiation therapy, additional chemotherapy is often given after surgery. If patients did not receive neoadjuvant therapy, they may be treated with both chemotherapy and radiation therapy after surgery.
Strategies to improve treatment
The progress that has been made in the treatment of rectal cancer has resulted from improved surgical techniques, the development of adjuvant and neoadjuvant chemotherapy and radiation therapy treatments and participation in clinical trials. Future progress in the treatment of rectal cancer will result from continued participation in appropriate clinical trials. Currently, there are several areas of active exploration aimed at improving the treatment of stage III rectal cancer.
New Adjuvant Chemotherapy Regimens: Several new chemotherapy drugs show promising activity for the treatment of advanced or recurrent rectal cancer. Development of new multi-drug chemotherapy treatment regimens that incorporate new or additional anti-cancer therapies for use as neoadjuvant and/or adjuvant treatment is an active area of clinical research.
Laparoscopic surgery: Laparoscopic surgery is used for many types of surgery with the short-term advantages of less pain, fewer wound complications, quicker post-operative recovery, and shorter hospital stays. Instead of making one long incision in the abdomen, the surgeon makes several smaller incisions. Special long instruments are inserted through these incisions to remove part of the rectum and lymph nodes. One of the instruments has a small video camera on the end, which allows the surgeon to see inside the abdomen. Once the diseased part of the rectum has been freed, one of the incisions is made larger to allow for its removal.
Laparoscopic-assisted surgery appears to be about as likely to be curative as the standard approach for earlier-stage cancers.1 However, there is still limited information from randomized trials about the approach. In addition, laparoscopic surgery requires special expertise and patients need to be treated by a skilled surgeon who has done a lot of these operations.
Improved Approaches to Radiation Therapy: As the technology for radiation therapy has evolved, important advances have been made in the ability of physicians to precisely target the area of the cancer. The goal is to deliver effective doses of radiation to the cancer while sparing healthy tissue to the extent possible. One newer approach to delivering radiation therapy is intensity modulated radiation therapy (IMRT). IMRT starts with a three-dimensional image of the cancer, and allows physicians to deliver different doses of radiation to different areas. The potential advantages for patients include both better tumor control and fewer side effects.
Targeted Therapies: Targeted therapies are anticancer drugs that interfere with specific pathways involved in cancer cell growth or survival. Some targeted therapies block growth signals from reaching cancer cells; others reduce the blood supply to cancer cells; and still others stimulate the immune system to recognize and attack the cancer cell. Depending on the specific “target”, targeted therapies may slow cancer cell growth or increase cancer cell death. Targeted therapies may be used in combination with other cancer treatments such as conventional chemotherapy. Targeted therapies that have shown a benefit for selected patients with advanced rectal cancer include Avastin® (bevacizumab), Erbitux® (cetuximab), and Vectibix® (panitumumab).
Managing Side Effects: Techniques designed to prevent or control the side effects of cancer and its treatments are called supportive care. Side effects not only cause patients discomfort, but also may prevent the delivery of therapy at its planned dose and schedule. In order to achieve optimal outcomes from treatment and improve quality of life, it is imperative that treatment is delivered as planned and that side effects resulting from cancer and its treatment are appropriately managed.
Reference:
1 Jayne DG, Thorpe HC, Copeland J et al. Five-year follow-up of the Medical Research Council CLASICC trial of laparoscopically assisted versus open surgery for colorectal cancer. British Journal of Surgery. 2010;97:1638-45.
Stage IV Rectal Cancer
Overview
Following clinical evaluation of rectal cancer, the cancer is referred to as Stage IV rectal cancer if the final evaluation shows that the cancer has spread to distant locations in the body, which may include the liver, lungs, bones, or other sites.
A variety of factors ultimately influence a patient’s decision to receive treatment of cancer. The purpose of receiving cancer treatment may be to improve symptoms through local control of the cancer, increase a patient’s chance of cure, or prolong a patient’s survival. The potential benefits of receiving cancer treatment must be carefully balanced with the potential risks of receiving cancer treatment.
The following is a general overview of the treatment of Stage IV rectal cancer. Circumstances unique to your situation and prognostic factors of your cancer may ultimately influence how these general treatment principles are applied. The information on this Web site is intended to help educate you about your treatment options and to facilitate a mutual or shared decision-making process with your treating cancer physician.
Most new treatments are developed in clinical trials. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Clinical trials are available for most stages of cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. To ensure that you are receiving the optimal treatment of your cancer, it is important to stay informed and follow the cancer news in order to learn about new treatments and the results of clinical trials.
Certain patients with Stage IV rectal cancer can be cured of their cancer and others derive meaningful palliative benefit from treatment. Patients with Stage IV rectal cancer can be broadly divided into two groups: those with cancer that may be possible to remove with surgery and those with more widespread cancer.
Treatment of extensive stage IV rectal cancer
While some patients have a single site of metastatic cancer that can be treated with curative intent, the majority of patients with Stage IV rectal cancer have more widespread cancer that cannot be completely removed with surgery.
If the cancer is extensive but not causing symptoms, treatment oven involves chemotherapy. Several different chemotherapy regimens are available, and the choice of which to use will depend on factors such as your health and previous treatment history. In some cases, chemotherapy may shrink the cancer enough that surgery to remove it becomes possible.
Chemotherapy may be given in combination with other drugs known as targeted therapies. Targeted therapies are anticancer drugs that interfere with specific pathways involved in cancer cell growth or survival. Some targeted therapies block growth signals from reaching cancer cells; others reduce the blood supply to cancer cells; and still others stimulate the immune system to recognize and attack the cancer cell. Depending on the specific “target”, targeted therapies may slow cancer cell growth or increase cancer cell death.
Targeted therapies that have shown a benefit for selected patients with metastatic colorectal cancer include Avastin® (bevacizumab), Erbitux® (cetuximab), and Vectibix® (panitumumab). Avastin blocks a protein (VEGF) that plays a key role in the development of new blood vessels. By blocking VEGF, Avastin deprives the cancer of nutrients and oxygen and inhibits its growth. Erbitux and Vectibix slow cancer growth by targeting a protein known as EGFR. Cancers with certain gene mutations are unlikely to respond to Erbitux or Vectibix, and tests are available to detect these mutations before treatment decisions are made.
If patients are experiencing symptoms from their rectal cancer, they may also receive treatments such as radiation therapy, surgery, or stenting to relieve problems such as bowel obstruction.
Treatment of metastatic rectal cancer to a single site
Rectal cancer may spread (metastasize) to the liver, lung or other locations in the body. When the site of metastasis is a single organ, such as the liver or lungs, patients may benefit from local treatment directed at that single site of metastasis
Highly selected patients with isolated areas of rectal cancer can be cured if the primary cancer in the rectum and the isolated area of cancer outside the rectum can be surgically removed.
Treatment of the liver: The most common site of metastasis for patients with rectal cancer is the liver. When it’s possible to completely surgically remove all liver metastases, surgery is the preferred treatment. Some patients may have both the liver and the rectum treated in a single operation, and others may have two operations: one to treat the rectum and one to treat the liver. Chemotherapy or chemotherapy plus radiation therapy may be used before and/or after surgery.
Although surgery offers some patients the chance for a cure, a majority of patients with liver metastases are not candidates for surgery because of the size or location of their tumors or their general health. Some of these patients may become candidates for surgery if initial treatment with chemotherapy shrinks the tumors sufficiently. If the tumors continue to be impossible to remove surgically, other liver-directed therapies may be considered. These other therapies include radiofrequency ablation (use of heat to kill cancer cells), cryotherapy (use of cold to kill cancer cells), delivery of chemotherapy directly to the liver, and radiation therapy. Relatively little information is available from clinical trials about the risks and benefits of these other approaches, but they may benefit selected patients.1
Strategies to improve treatment
While some progress has been made in the treatment of Stage IV rectal cancer, the majority of patients still succumb to cancer and better treatment strategies are clearly needed. Future progress in the treatment of rectal cancer will result from continued participation in appropriate clinical trials. Currently, there are several areas of active exploration aimed at improving the treatment of rectal cancer.
New Approaches to Treating Liver Metastases: Researchers continue to explore news ways to treat cancer that has spread to the liver. One approach that is being evaluated is radioembolization This strategy uses radioactive microspheres (small spheres containing radioactive material). The small spheres are injected into vasculature of the liver, where they tend to get lodged in the vasculature responsible for providing blood and nourishment to the cancer cells. While lodged in place, the radioactive substance spontaneously emits radiation to the surrounding cancerous area while minimizing radiation exposure to the healthy portions of the liver.2 Researchers are also exploring alternatives to radiofrequency ablation for the destruction of liver tumors, as well as new approaches to delivering chemotherapy to the liver.
New Chemotherapy Regimens: Development of new multi-drug chemotherapy treatment regimens that incorporate new or additional anti-cancer therapies is an active area of clinical research.
New Approaches to Targeted Therapy: Targeted therapies such as Avastin, Erbitux, and Vectibix already play a role in the treatment of selected patients with advanced colorectal cancer, but researchers continue to explore new targeted therapies as well as new ways of using existing drugs. Developing tests to predict which patients are most likely to respond to which drugs is also an important focus of research. Tests to identify certain gene mutations in the cancer are already available, and can help guide the use of Erbitux and Vectibix.
Managing Side Effects: Techniques designed to prevent or control the side effects of cancer and its treatments are called supportive care. Side effects not only cause patients discomfort, but also may prevent the delivery of therapy at its planned dose and schedule. In order to achieve optimal outcomes from treatment and improve quality of life, it is imperative that treatment is delivered as planned and that side effects resulting from cancer and its treatment are appropriately managed.
References:
1 Alsina J, Choti MA. Liver-directed therapies in colorectal cancer. Seminars in Oncology. 2011;38:651-567.
2 Hendlisz A, Van den Eynde M, Peeters M, et al. Phase III Trial Comparing Protracted Intravenous Fluorouracil Infusion Alone or With Yttrium-90 Resin Microspheres Radioembolization for Liver-Limited Metastatic Colorectal Cancer Refractory to Standard Chemotherapy. Journal of Clinical Oncology. 2010;28:3687-94.