Good News About Cancer: Revolutionary Treatments Are Saving Lives

Photo by Kristine Larsen

ancer is still a formidable foe, but in the last few years alone, scientists have gained intimate knowledge of this enemy and are using it to outmaneuver these deadly cells—prolonging life and improving cure rates for thousands of patients. As science learns more and more about human genetic makeup, researchers have identified scores of genes implicated in various cancers.

Today, hit-or-miss therapies are giving way to carefully targeted drugs that attack these genes at the most basic level, subverting the abnormal mechanisms they use to survive and grow.

The drug Avastin, for example, blocks the growth of blood vessels that carry vital nutrients to cancer cells. Already used for several years to slow the growth of advanced colon and lung cancer, Avastin was approved for treatment of metastatic breast cancer in February. Doctors say they are just beginning to tap its potential. One big problem: The drug can cost as much as $92,000 a year.

“For the past 50 years oncologists tested hundreds of thousands of compounds on cancer cells to see if they would slow the growth or destroy them,” says Gabriel N. Hortobágyi, M.D., director of the multidisciplinary breast cancer research program at the University of Texas M.D. Anderson Cancer Center in Houston. “It was very inefficient.”

Now “we can profile cancer genes, understand what makes them abnormal, then look for very specific ways to disrupt those processes,” Hortobágyi says. “This is a revolution. Instead of developing 50 drugs over 50 years, we’re developing 10 or 20 drugs every year.”

According to a survey released in March, one-quarter to one-half of all new cancer treatments that enter later-stage clinical trials are eventually proved to be effective. And “this pattern of successes has become more consistent over time,” say the researchers at the University of South Florida who conducted the review.

At the same time, older therapies are being refined, almost reinvented. Radiation therapy now uses what one oncologist calls “Star Trek technology” to target cancers with great precision, sparing healthy tissue and reducing side effects.

Progress is measurable, says John Mendelsohn, M.D., president of M.D. Anderson. “When I was born, only about a third of all cancer patients lived five years or more. Today, two-thirds do.”

Almost 1.5 million people, the American Cancer Society says, will be diagnosed with cancer in 2008, many with lung, breast, colon or prostate cancer. Because age is a primary risk factor for cancer, 77 percent of all cancers will occur in people age 55 and older.

Here are some new treatment developments for these four cancers:

Lung Cancer
Researchers last month announced they had identified genetic quirks that increase the risk of lung cancer in smokers and former smokers by 21 to 81 percent. Three international teams each pinpointed the same genetic link to cancer risk.

Smoking accounts for 85 to 90 percent of all lung cancers. But only about 15 percent of smokers and ex-smokers develop cancer. The findings on genetic links, reported in Nature and Nature Genetics, are a major step forward and should help researchers identify people at high risk for nonsmall cell lung cancer, the most common form of the disease. Identifying those at high risk is key because there are usually no symptoms until the cancer is in an advanced stage and harder to treat.

Another treatment advance: image-guided radiation therapy. “I would guess almost everyone living in the U.S. is now within an hour of a center that has this,” says Kenneth Rosenzweig, M.D., a radiation oncologist at Memorial Sloan-Kettering Cancer Center in New York. The system gives radiologists a clearer, more accurate picture of the lung tumor, allowing them to target it more precisely. Better targeting also reduces the number of treatments needed for early-stage lung cancer from 30 to 40 treatments over two months to three or four spread over one week, Rosenzweig says.

For those with advanced cancer confined to the lungs, survival rates have gone “from nothing to as high as 35 percent with chemo and radiation or surgery,” says Roy Herbst, M.D., chief of thoracic medical oncology at M.D. Anderson.

Breast Cancer
There are at least four major subtypes of breast cancer, and researchers have developed specific therapies for each—with some dramatic results.

The effectiveness of a new treatment to prevent a recurrence of estrogen-fueled cancer—the most common type in postmenopausal women—was confirmed in March by two major studies at Massachusetts General Hospital and at the University of Vermont College of Medicine. The findings suggested that women can protect themselves by taking an aromatase inhibitor (AI) drug after finishing a five-year course of tamoxifen.

While tamoxifen is a potent estrogen blocker, after five years it has been known to stimulate estrogen production, especially in older women. AIs also block estrogen but with a different mechanism, and they can be taken safely for years. Long-term protection is key because half of those with this type of breast cancer who relapse do so after five years.

“Older women in their 70s took AIs and tolerated them as well as younger women,” says Nancy Lin, M.D., an oncologist at Boston’s Dana-Farber Cancer Institute who reviewed the studies.

“This is a real advance and one that older patients with this cancer should know about,” says Larry Norton, M.D., deputy physician-in-chief for breast cancer programs at Memorial Sloan-Kettering.

Another striking development—two drugs that target a highly aggressive type of breast cancer, HER-2 positive. About one in five breast cancers is HER-2 positive. In 2006 a blockbuster drug, Herceptin, previously used only in late-stage cancer, was approved by the Food and Drug Administration for use in the early stages. It now prevents a relapse in half of the women who were likely to have had a recurrence. This year, a second drug, Tykerb, was approved for women with advanced HER-2 positive breast cancer who did not respond well to Herceptin. Tykerb acts to inhibit two key proteins, while Herceptin blocks one.

“This was one of the worst types of breast cancer, with one of the worst outcomes,” says Eric Winer, M.D., chief of breast oncology at Dana-Farber. “Now it is highly curable in many, many women with early HER-2 cancer. For those with more advanced HER-2 cancer, these drugs mean they can live years longer.”

Winer predicts that in the next two years doctors will have several more drugs that target HER-2 positive cancer. “This may be the first type of breast cancer we look back on and say, ‘This used to kill but it doesn’t anymore,’ ” he says.

Colon Cancer
For 50 years there was only one drug to treat colon cancer. Today five new drugs—three chemo agents and two targeted therapies—have been integrated into highly effective treatments, says Raymond Dubois, M.D., a specialist in this cancer and the provost of M.D. Anderson.

Of the two targeted therapies, one (Avastin) works to starve the cancer cells, while the other (Erbitux or Vectibix) blocks a protein on the surface of the tumor cells.

FOLFOX, a cocktail of new chemo agents,  changed the standard of treatment for advanced colon cancer, improving survival rates and reducing the likelihood of relapses among patients whose colon cancer spread into the lymph nodes, says Robert J. Mayer, M.D., director of the center for gastrointestinal oncology at Dana-Farber.

“With these new therapies the median survival rate for those with late-stage colon cancer has moved from six to nine months to upwards of two years,” Mayer says.

The protein inhibitors, however, are toxic and expensive, $15,000 a month, and in 45 percent of patients they appear to have no effect, says Axel Grothey, M.D., chairman of the colorectal cancer group at the Mayo Clinic in Rochester, Minn.

He predicts that by the end of the year doctors will have a test that will allow them to exclude patients unable to benefit from this therapy, saving them debilitating side effects and expense. “This opens a new door” to personalized medicine, Grothey says.

Prostate Cancer
Death threats—ostensibly from prostate cancer patients—were sent to several doctors who helped persuade the FDA not to approve a new drug, Provenge, which a small study suggested might prolong the survival of men with advanced cancer. But the FDA may reconsider its 2007 decision after the results of a larger clinical trial are announced this fall. If the drug—a vaccine to stimulate the body’s own immune system to fight the cancer—does work, “that would be a real sea change, because immunotherapy in general has not been successful in any cancers,” says Philip Kantoff, professor of medicine at Harvard University and the leader of Dana-Farber’s prostate cancer program.

While older patients with other cancers are often undertreated, a growing census holds that “there is a significant amount of overtreatment” in older men with localized prostate cancer, says Theodore DeWeese, M.D., chair of the Department of Radiation Oncology and Molecular Radiation at the Johns Hopkins School of Medicine in Baltimore. He and other oncologists say older men with low-grade prostate cancer—and especially men with another disease—are good candidates for “watchful waiting.” That means having an annual biopsy, testing levels of PSA—a protein that can signal cancer—and forgoing treatment unless those tests indicate some danger.

Barbara Basler is a senior editor on AARP Bulletin staff.