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Proton Therapy: The Future of Cancer Care

Publication: Dallas Medical Journal

“Proton therapy has been effective in treating a wide variety of tumors, while helping to preserve quality of life for our patients,” said Andrew Lee, M.D., M.P.H., medical director, Texas Center for Proton Therapy and the first physician in North America to utilize pencil-beam proton therapy to treat cancerous tumors. In Dr. Lee’s practice, patients find precision targeted therapy in the only proton therapy center in the region.

Proton beam therapy is an advanced type of radiation therapy aimed at destroying cancerous cells using accelerated protons. The treatment offers sub-millimeter precision that delivers high-energy proton beams directly to tumors, minimizing damage to surrounding healthy tissue.

“Pencil-beam scanning enables greater conformality in tumor treatments compared to traditional proton beam therapy, allowing us to reach levels of precision that was not possible even 10-15 years ago,” Dr. Lee said.

Pencil-beam Scanning in Proton Therapy

All three treatment rooms at Texas Center for Proton Therapy feature spot-scanning proton therapy, known as pencil-beam scanning. Using an ultra-fine proton beam with pencil-point precision across each three-dimensional layer of the tumor, the tumor is essentially delicately “painted” with spots of radiation one slice at a time until the entire 3D tumor volume is covered. It’s the ideal technology for irregularly shaped tumors near sensitive areas.

Pencil-beam scanning capability also is a prerequisite for a proton therapy center to offer intensity modulated proton therapy (IMPT). This type of highly specialized proton therapy delivers a precise dose of protons to often tight spaces through a combination of pencil beam proton therapy and sophisticated treatment planning algorithms and offers one of the most advanced forms of radiation therapy in the world.

Texas Center for Proton Therapy is one of only a few centers in the country offering pencil-beam scanning with on-board volumetric cone beam CT. With all three treatment rooms capable of pencil-beam scanning, Texas Center for Proton Therapy is the largest pencil-beam proton center in the state.

“This type of therapy is non-invasive, performed as an outpatient, and patients can maintain their current quality of life during and after treatment,” Dr. Lee said, emphasizing the benefits of proton therapy as a treatment modality.

Types of Cancer Targeted by Proton Therapy

Proton therapy has effectively treated a wide variety of cancers (whether small or large) in virtually every part of the body. As part of a multidisciplinary treatment regimen, proton therapy has been shown in studies to increase a patient’s ability to receive other concurrent or sequential therapies, such as chemotherapy and/or surgery. Proton therapy may also treat tumors in sensitive areas where conventional therapy may not be the best option.

Proton therapy may be used to treat virtually any tumor that is treated with standard radiation, but it is particularly applicable for treating certain cancers including:

Brain and Spine Tumors

During treatment, a narrow proton beam is guided to focus the highest energy of the beam at the location of the tumor in the brain or spine. While the proton beam is being delivered, it can also be designed to conform to the shape, size, and depth of tumors, limiting excess radiation near surrounding areas of the body.

The accuracy of proton therapy makes it particularly useful in treating:

  • Tumors near sensitive areas of the brain, skull base, or spine
  • Patients who require postoperative radiation therapy
  • Patients who have recurrent brain tumors following treatment
  • Select patients, including those with brain metastases, who may be candidates for stereotactic proton therapy
  • Patients with benign tumors
“Preserving adjacent tissue is of extreme importance,” Dr. Lee noted. “Once the proton beam enters the body at the targeted tumor, less radiation is delivered before and after the tumor. After the proton beam hits the tumor, little to no radiation is delivered to nearby tissue.”

Breast Cancers

For cancers of this sensitive area of the body near several vital organs, proton therapy can deliver high doses of radiation to destroy cancerous cells while preserving other nearby tissue. This precise treatment minimizes exposure to the heart, lungs, and healthy tissue near the breast, and can be used for breast cancer patients even following lumpectomy or mastectomy. Proton therapy may also be used in select cases in which cancer has recurred following surgery and/or radiation or has spread to other parts of the body. We routinely treat breast cancer patients that require radiation to their breast or chest wall as well as the adjacent lymph nodes. Proton therapy allows us to comprehensively treat these cases while minimizing exposure to the underlying heart, lungs, and brachial plexus.

Childhood Cancers

While childhood cancers are rare – accounting for less than 1% of all cancer diagnoses – they remain the most common cause of disease-related deaths among children outside the newborn period, according to the American Society of Clinical Oncology. Types of childhood cancer treated with proton therapy include brain and spine tumors, chordoma, craniopharyngioma, ependymoma, Ewing sarcoma, germinoma and other germ cell tumors, lymphoma, medulloblastoma, neuroblastoma, rhabdomyosarcoma, and sarcomas.

“A cancer diagnosis may be one of the most difficult challenges a person will face, and this point is particularly relevant for young patients and their families,” Dr. Lee said. “We are uniquely positioned to treat children with cancer and provide the support needed for their families as they make this journey.”

Texas Center for Proton Therapy specializes in pediatric oncology and uses national protocols developed for children. The center has specialized pediatric equipment pediatric sub-specialists, clinical trials specifically for children, and has a child life specialist on staff to support patients and families.

Gastrointestinal, Genitourinary, and Gynecologic Cancers

Proton therapy is effective in treating many types of gastrointestinal cancers, including esophageal, liver, pancreatic, and stomach cancer. This may also include patients with recurrent or metastatic disease. Patients with genitourinary cancers, including bladder, prostate, and testicular cancer, and women with gynecologic cancers, including cervical, ovarian, and uterine cancers, also find benefit in proton therapy.

For Dr. Lee, the extensive applicability of this treatment method in such a wide variety of cancers, include tiny tumors to rather large volumes, makes proton therapy one of the most unique advancements in cancer care available today. “The breadth of cancers that proton therapy can treat is a contrast to the specific and small areas we can use this therapy, which is a tremendous advantage for our patients and their quality of life.”

Head and Neck Cancers

Treating head and neck cancers through highly targeted treatment is essential to maintaining the who the patient is and how they proceed through life. Typically, cancers of the head and neck begin in the mucosal surfaces or the tissue lining of organs. Proton therapy’s ability to minimize stray radiation exposure may also improve a patient’s ability to tolerate concurrent chemotherapy. Head and neck cancers treated with proton therapy include cancers of the:

  • Oral cavity
  • Nasal cavity
  • Paranasal sinuses
  • Lymph nodes
  • Larynx
  • Naso and Oropharynx
  • Salivary glands
  • Peri-orbital structures

Lung Cancers

Lung cancer is still responsible for the most cancer-related deaths in both men and women in Texas, with the most common type, non-small cell lung cancer, accounting for approximately 80-85% of lung cancers. Lung cancer can be treated and is often preventable, but today, only 16% of men and 23% of women live more than five years beyond their initial diagnosis. Treatment options for lung cancer vary depending on the stage and type of the cancer. Proton therapy has been shown to be an effective treatment for lung cancers and should be considered, if the patient is a candidate, to preserve as much lung function as possible while improving survival rates. Proton therapy can be used for relatively large tumors with or without concurrent chemotherapy and also small tumors utilizing stereotactic approaches, which may be less than five treatments.

Lymphomas and Sarcomas

Both categories of lymphoma, Hodgkin lymphoma and non-Hodgkin lymphoma, vary in behavior, treatment reaction, and how each spread. However, proton therapy has been shown to be effective in treating both types. This is particularly important in young patients and in those individuals, who may have received neoadjuvant chemotherapy.

Cancers of connective tissue, sarcomas, are also treatable via proton therapy. This may be done preoperatively, which is preferred, or postoperatively. Whether they are soft tissue sarcomas, originating from cells of muscle, fat, nerve, fibrous tissue, deep skin tissue, or blood vessels; or bone sarcomas such as osteosarcoma or Ewing sarcoma; proton therapy can provide the precision treatment that can help save patients’ lives but also preserve function.

Connecting for Care

Dr. Lee, the physicians and staff at Texas Center for Proton Therapy greatly value the relationships with physicians in the medical community and the opportunity to improve oncologic care in the region.

“We consider the proton therapy treatment we offer to be part of the overall approach to care offered by the patient’s care team,” Dr. Lee said. “Collaborating with other physicians to improve and save lives together is truly an honor.”

For more information visit TexasCenterForProtonTherapy.com.

This article appeared in the October issue of Dallas Medical Journal.

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