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Medical Edge Newspaper Column from Mayo Clinic

PROSTATE CANCER CAN BE TREATED WITH PRECISION-GUIDED RADIATION

DEAR MAYO CLINIC: My father was recently diagnosed with prostate cancer, and his doctor recommended radiation treatment to begin immediately. Dad changed doctors to get a second opinion and was told the same thing. Now he wants another opinion because he’s afraid the radiation will do more harm than good by killing healthy cells. He said he’s read there are improved techniques in radiation treatment for prostate cancer that are less damaging to healthy tissue. Is he right? — Stowe, Vt.

ANSWER: Yes, there is an alternative to traditional delivery of radiation for prostate cancer. Called “Precision-Guided Prostate Cancer Treatment,” it was developed at Mayo Clinic. Wayne State University, the University of Michigan and the University of California, San Francisco, offer similar procedures, and other sites are likely to be in the process of implementing the technique.

This treatment consists of a precision-guided procedure in which the radiation beam covers the entire target — the cancer — with sufficiently high radiation doses to destroy it. At the same time, radiation of healthy tissue nearby is minimized by an internal marker system implanted into the prostate itself. This improves precision so fewer healthy cells are destroyed by an overly broad application of radiation.

Some background on radiation treatments may be helpful here. Conventional radiation therapy for prostate cancer targets the cancer by combining two guidance systems: internal imaging from CT or magnetic resonance scans, and external markings on the skin and skeletal points. There is imprecision in this system because the prostate can move. In addition, the correlation between skin and skeletal markings to nearby soft-tissue organs — the bladder, rectum and penile bulb — may also be imprecise.

To correct for this imprecision, radiation oncologists often enlarge the radiation beam by 10 to 15 millimeters in each dimension to make sure that all parts of the prostate — and the cancer — receive sufficient radiation.

To improve the “aim” of radiation, researchers developed a “direct hit” procedure. In it, we insert into the prostate four small markers that are visible to the radiation beam so that it homes in on the prostate. Our studies show that with this technique, we can confine the beam to within 2 millimeters of the target. This assures we hit the entire cancer — yet spare healthy surrounding tissues.

— Thomas Pisansky, M.D., Radiation Oncology; Mayo Clinic, Rochester, Minn.

Additional Resources:
Treatment of Prostate Cancer
Appointment Information
Precision Guided Prostate Cancer Treatment
More Information on Prostate Cancer

DEAR MAYO CLINIC: My daughter is in nursing school and says that, since I’m 55, I should be screened for colon cancer. I’ve never heard of this as a routine thing. I’m uncomfortable talking about it with friends, and I never get the same doctor twice at the local clinic, so I don’t feel right there, either. Now she’s got me worried. Should I be screened? — Sandpoint, Idaho

ANSWER: Yes. Here’s why: Cancer of the colon and rectum (colorectal cancer) is the second-leading cause of cancer-related deaths in both women and men. Studies show that in 2003, approximately 57,000 Americans died of colorectal cancer.

Yet studies also show that many people your age have not had appropriate screening.

Your daughter, as a nurse-in-training, is in an excellent position to help you find a caregiver with whom you feel comfortable discussing screening options. That’s the first step.

Next, meet with your provider to go over possible risk factors for colorectal cancer, such as a history of colorectal polyps or cancer, inflammatory bowel disease (also called ulcerative colitis or Crohn’s disease), or a family history of colorectal and other cancers.

In the absence of any known colorectal cancer risk factors, the American Cancer Society endorses the following screening options beginning at age 50: 1) yearly fecal occult blood test, 2) flexible sigmoidoscopy every five years, 3) yearly fecal occult blood test plus flexible sigmoidoscopy every five years, 4) double-contrast barium enema every five years, or 5) colonoscopy every 10 years. Discuss with your physician which of the available screening options is right for you.

Think of it this way: You probably watch what you eat and have your cholesterol levels tested. In your age group, a baseline colorectal cancer screening exam is in the same class of prudent self-care and is one of the best preventive measures you can easily initiate.

— Paul Limburg, M.D., Gastroenterology, Mayo Clinic, Rochester, Minn.

Additional Resources:
Treatment of Colon Cancer
Appointment Information
More Information on Colorectal Cancer

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Medical Edge from Mayo Clinic is an educational resource and doesn’t replace regular medical care. To e-mail a question, go to www.mayoclinic.org, or write: Medical Edge from Mayo Clinic, c/o TMS, 2225 Kenmore Ave., Suite 114, Buffalo, N.Y., 14207. For health information, visit www.mayoclinic.com.