Scanning for Breast Cancer
Thursday, June 01, 2000
Proton Treatment Center modifications to benefit breast cancer patients
For the past ten years, the Loma Linda University Medical Center Proton Treatment Center has built a solid reputation for treating prostate cancer patients with non-invasive proton therapy. More than 3,000 men have completed proton treatment; studies show the overall disease-free survival rate is 89 percent.
Now, Loma Linda University engineers, physicists, and physicians are turning their attention to the needs of women with breast cancer.
One out 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 United States 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 past the age of 50.
Several risk factors are known to increase a woman's chance of developing cancer. A woman may be at increased risk if she has a family history of the disease, if she has her first child after the age of 30, or if she has no children. More than 70 percent of women who develop breast cancer, however, have no known risk factors.
The best chance for successful treatment occurs when the cancer is found early. Mammograms--special x-rays of the breast--can detect more than 90 percent of all breast cancers and should be part of every woman's breast health program, along with breast self-examination and physical examination by a physician.
If breast 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 therapy, and chemotherapy. Within the next two years, these options will increase as Loma Linda personnel begin enhancing and modifying the proton beam therapy system by adding 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 are required for the proton accelerator, the beam transport system, and the beam delivery system. These enhancements have already begun with grant funding 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 Treatment Center will be capable of "scanning." This will allow the new technology to be applied to mainstream proton therapy, including improved beam-focusing control for the treatment of breast cancer.
Following 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 breast and sometimes in both breasts. As the tumor cells multiply at their site of origin, some cells migrate into the lymphatic channels located profusely 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 within the capillaries of the lungs and continue multiplying, forming masses extending into surrounding tissues.
Other cells continue through the blood stream to 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 the 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 lymphatics and deep chest wall lymphatics between the ribs become involved when tumors grow into these tissues.
A window of opportunity exists between the time normal breast cells first transform and become malignant (become cancer cells) and when they migrate through the lymphatics to the blood stream. During this period of time, the patient can be cured of her disease with loco-regional therapy.
Protons- new option
As mentioned, surgery, chemotherapy, and x-radiation have been 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 two years, with the modifications taking place at Loma Linda University Medical Center'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 dimensions, 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 can be expected to result in another major reduction in patient morbidity and improved cancer control.
Engineers, physicists, and physicians at Loma Linda University and 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.
Proton therapy milestones
- 1946 Proton beam treatment for medical purposes is proposed for the first time by Robert Wilson, PhD.
- 1955 Proton treatment begins at Berkeley Radiation Laboratory.
- 1970 Loma Linda University Medical Center begins planning for charged-particle therapy program.
- 1971 Loma Linda University investigators develop the world's first computer-assisted treatment planning system.
- 1987 Engineering design of Loma Linda University synchrotron begins at Fermi National Accelerator Laboratory.
- 1988 Groundbreaking is held for the Loma Linda University Proton Treatment Center.
- 1988 Congress grants $8.5 million for Proton Treatment Center; Department of Energy grants $11.1 million.
- 1989 Loma Linda University Medical Center synchrotron is commissioned at Fermi National Accelerator Laboratory.
- 1990 Fermilab tests 250-million-electron-volt accelerator; synchrontron is shipped.
- 1990 First patient is treated at Proton Treatment Center.
- 1991 Second beam line is commissioned in January; treatment for brain, head, and neck tumors begins.
- 1992 Groundbreaking for $20.3 million Loma Linda University proton and cancer research laboratories is held.
- 1992 A-level floor of Proton Treatment Center is named in honor of U.S. Congressman Jerry Lewis.
- 1994 Second and third gantries begin clinical operation.
- 1994 NASA and Loma Linda University plan research to protect astronauts from space radiation.
- 1996 2,000th patient is treated.
- 1996 Cancer research laboratories are dedicated.
- 1997 NASA radiobiology research begins at Loma Linda University.
- 1998 Radiation medicine begins treating 100 proton therapy patients and 100 photon (x-ray) patients per day; 4,000th patient is treated by year end.
- 1998 Clinical trials target lung cancer and age-related macular degeneration.
- 1999 Clinical trials target liver cancer.
- 1999 $1.3 million raised since
- 1991 for research by Ken Venturi Loma Linda Proton Charity Invitational golf tournament
