Radiation Therapy for Cervical Cancer
Radiation therapy, or radiotherapy, is a common way to treat cervical cancer. Doctors who specialize in treating cancers with radiation are known as radiation oncologists. During radiation therapy, high-energy x-rays are used to kill cancer cells. Radiation therapy can be administered by a machine that aims x-rays at the body (external beam radiation) or by placing small capsules of radioactive material directly into the cervix (internal or implant radiation or brachytherapy). Many patients receive both kinds of radiation therapy. In stage I cervical cancer, radiation therapy may be used instead of surgery, or it may be used after surgery to destroy remaining cancer cells. In stage IB-IVA cervical cancer, radiation therapy is administered concurrently with chemotherapy.
External Beam Radiation Therapy
External beam radiation therapy (EBRT) for cervical cancer is administered on an outpatient basis, 5 days a week for several weeks. EBRT begins with a planning session, or simulation, where marks are placed on the body and measurements are taken in order to line up the radiation beam in the correct position for each treatment. A program of daily treatments is then begun where the patient lies on a couch and is treated with radiation from multiple directions to the pelvis. External beam radiation therapy for cervical cancer is administered on an outpatient basis for approximately 4 to 6 weeks.
A combination of external beam radiation therapy and implant radiation is used to increase the dose of radiation administered to the cancer. Implant or internal radiation is further described in the section below. When these two methods are combined, the external beam radiation therapy is given for 4-6 weeks, and the final “boost” of radiation to the cervix is given with the implant radiation.
Although patients do not feel anything while receiving radiation treatment, the effects of radiation gradually build up over time. Many patients become tired as treatment continues. It is also common for patients to experience loose stools or diarrhea. Urination may become more frequent or uncomfortable. Some patients may experience loss of pubic hair or irritation of the skin. After the radiation therapy is completed, the vagina can become narrower and less flexible. This can make sexual relations painful and make future pelvic examinations difficult. Patients are often taught how to use a dilator to maintain the pliability of the vagina. Finally, radiation therapy to the pelvis can stop the ovaries from functioning, thereby causing younger women to enter menopause early.
Implant Radiation Therapy
Implant radiation, sometimes referred to as brachytherapy, refers to treatment where radioactive material is placed directly into the cervix. Placing the radiation in this manner allows a high radiation dose to be delivered directly to the cancer, while reducing radiation to surrounding normal organs, such as the rectum and bladder. During a procedure in the operating room, a small device is placed into the cervix and vagina. This device is later “loaded” with the radiation capsules while the patient is in a lead-shielded hospital room. The radioactive material is left in place for 1-3 days. This procedure may be performed once or twice during the course of treatment. The patient is discharged from the hospital once the device is removed from the cervix.
Many centers are administering the implant radiation on an outpatient basis using a slightly different technique called “high-dose rate (HDR) brachytherapy.” With this procedure, a device is inserted into the cervix and vagina in the radiation therapy department and the patient remains with the radiation for only 30 minutes to one hour. This procedure is generally repeated weekly, approximately 3 to 5 times during the course of treatment. HDR brachytherapy is a newer technique and is not yet widely available. The results from early experience demonstrate that HDR brachytherapy appears to be just as effective as traditional implant radiation, but avoids a hospital stay.
A less commonly used method of brachytherapy is interstitial (into the tissue) implant. With this method, the patient is placed under general anesthesia and fine tube like needles are placed into the cancer and immediate tissue around it in a manner to fit the shape of the cancer. The tube-like needles are later “loaded” with the radioactive seeds and the remaining steps are similar to what is done with implants.
In implant radiation therapy, the positioning of the device is critical to the effectiveness and safety of the treatment. Although the cervical cancer receives the highest radiation dose, the surrounding organs, such as the rectum and bladder, are also exposed to some radiation. Radiation injury to the rectum, bladder or bowel can occur and may cause pain or bleeding with urination or passage of stools. Less commonly, some patients will develop a fistula, which is an abnormal connection between the rectum or bladder and the vagina. At times, additional surgery may be necessary for repair of fistulas or other radiation injury.
Strategies to Improve Treatment
The progress that has been made in the treatment of cervical cancer has resulted from improved development of radiation treatments concurrent with chemotherapy and participation in clinical trials. Future progress in the treatment of cervical cancer will result from continued participation in appropriate clinical trials. Currently, there are several areas of active exploration aimed at improving radiation treatment of cervical cancer.
Supportive Care: Supportive care refers to treatments designed to prevent and control the side effects of cancer and its treatment. Side effects not only cause patients discomfort, but also may prevent the optimal 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 side effects resulting from cancer and its treatment are appropriately managed. For more information, go to Supportive Care.
Newer Radiation Techniques: EBRT can be delivered more precisely to the cervix by using a special CT scan and targeting computer. This capability is known as three-dimensional conformal radiation therapy, or 3D-CRT. The use of 3D-CRT appears to reduce the chance of injury to nearby body structures, such as the bladder or rectum. Since 3D-CRT can better target the area of cancer, radiation oncologists are evaluating whether higher doses of radiation can be given safely and improve the chance of cure.
Newer Radiation Machines: Most EBRT uses high energy x-rays to kill cancer cells. Some radiation oncology centers use different types of radiation that require special machines to generate. These different types of radiation, such as protons or neutrons, appear to kill more cancer cells with the same dose. Combining protons or neutrons with conventional x-rays is one method of radiation therapy being evaluated in clinical trials.
Preservation of Ovarian Function: A new procedure that involves the permanent placement of a section (cortical strip) from a patient’s ovaries into her forearm may preserve fertility and normal ovarian function in pre-menopausal women who are treated with radiation to the pelvic area or undergo the removal of their ovaries.
Researchers evaluated the surgical procedure in two women, a 35-year-old with advanced cervical cancer who was to undergo pelvic radiation and a 37-year-old with benign cysts on her ovaries who was to undergo an oophorectomy. Both patients had cortical strips removed from their ovaries and permanently transplanted to the forearm. The first patient received her transplant prior to radiation and the second patient received her transplant during the oophorectomy. Ten weeks following surgery, the transplant tissue in both patient’s forearms had resumed the production of ovarian hormones and the development of follicles (eggs). One patient has actually ovulated and the other patient is producing cyclical hormone levels indicative of ovulation. Besides normal hormonal function, the other end goal of this procedure is to be able to harvest eggs from the transplanted ovarian strips so that pre-menopausal patients having to undergo treatment that normally causes sterility can bear children.