New Proton Center 'Scanning' Method Will Help Breast Cancer Patients

For the past ten years, the Loma Linda University & Medical Center Proton Treatment Center has built a solid reputation for treating men with prostate cancer with non-invasive proton therapy. More than 3,000 men so far have completed proton therapy's course of treatment with studies showing the overall disease free survival rate at 89 percent.

Now, Loma Linda University engineers, physicists, and physicians are turning their attention to the needs of women with breast cancer.

One of every nine American women will develop breast cancer sometime during her life (if she lives to the age of 85). This year, 180,000 women in the U.S. will be diagnosed with invasive breast cancer and 43,500 will die of the disease. It is the most common form of cancer in women and the second leading cause of cancer death for women after lung cancer.

Every woman is at risk for breast cancer. A woman's chance of developing breast cancer increases as she grows older; 80 percent of all cancers are found in women over the age of 50. There are also several risk factors that can increase a woman's chances of developing cancer.

A woman may be at increased risk if she has family history of the disease, if she had her first child after the age of 30 or has no children. However, more than 70 percent of women who develop breast cancer have no known risk factors.

The best chance for successful treatment occurs when cancer is found early. Mammograms, or special x-rays of the breast, can detect more than 90 percent of all cancers and should be part of every woman's breast health program, along with breast self-exam and physical exam by a physician.

If a cancer is found early, it is more than 90 percent likely to be completely curable.

Until now, treatment options have included surgery, standard x-ray radiation therapy, and sometimes chemotherapy. Within the next year or so, those options will increase as Loma Linda University personnel begin enhancing and modifying the proton beam therapy system by adding the capability of a new technique known as "scanning." This new, non-invasive proton option will provide an extra dimension in the treatment of breast cancer minus the traditional side effects.

To accomplish this technique, numerous modifications must be made to the proton beam system. Enhancements must be made to the proton accelerator, the beam transport system, and the beam delivery system. These enhancements have already begun with funding provided by grants from the U.S. Departments of Energy and Defense.

With the completion of this work by the fall of 2001, the entire accelerator, beam transport line, and beam delivery system in the calibration/research room at the proton center will be capable of "scanning." This will allow this new technology to be applied to mainstream proton therapy, including improved beam-focusing control for the treatment of breast cancer.

Leading up to that point, here is a summary of how the process works:

Disease Process: Breast cancer is often multi-centric in origin, that is, it may begin in multiple sites within the breasts and sometimes in both breasts. As the tumor cells multiply at their site of origin, some cells migrate into the lymphatic channels profusely located throughout the breast. These channels or vessels carry the cells laterally to the axilla where they may become trapped and continue to multiply.

Cells may continue their journey superiorly through the lymph channels approaching the neck where they again may become trapped in lymph nodes. The cells may continue to multiply, escape and pass through the lymph vessels where they empty into large veins at the base of the neck. Once in the blood stream, they may become trapped with capillaries of the lungs and continue multiplying forming masses extending into surrounding tissues.

Other cells continue through the blood stream to the other organs such as bone, liver and brain. These organs frequently serve as hosts for metastatic breast cancer cells.

The second route of lymphatic spread from the breast is centrally to lymph nodes under the sides of the breast bone where the ribs attach. These lymph channels carry cells to the base of the neck, where they join those leading from the axilla and also enter nodes in that region eventually emptying into the blood stream.

Skin lymphatic and deep chest wall lymphatic between the ribs become involved when tumors grow into these tissues.

A window of time exists between the time normal breast cells first transform and become malignant (become cancer cells) and when they migrate through the lymphatic to the blood stream. During this period of time, the patient can be cured of her disease with loco-regional therapy.

Protons: A New Option

As mentioned earlier, surgery, x-radiation, and chemotherapy have been the primary treatment modalities for breast cancer.

Protons provide a new dimension for radiation oncologists, improving their ability to place radiation precisely within the delineated volume.

The superior distribution of the proton beam allows for its placement in the tumor while sparing surrounding healthy cells and tissue. The precision of proton therapy has been known for decades.

In about a year or so, with the modifications taking place at Loma Linda's Proton Treatment Center, protons can be safely placed into the breast and lymphatic vessels and nodes with much more precision than is now possible with standard x-ray therapy. Protons will provide increased precision in three-dimension, allowing physicians to design a treatment protocol that delivers optimal quantity of radiation to each of these regions while significantly reducing the total dose of radiation reaching normal cells and tissues.

This new technique will allow continued improvement in the treatment for breast cancer and can be expected to result in another major reduction in patient morbidity and improved cancer control.

Engineers, physicists, and physicians at Loma Linda University & Medical Center, trained and experienced in proton beam therapy, are currently working on bringing breast cancer into the mainstream of treatment protocols at the Proton Treatment Center .

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