Thousands of women could skip painful and detrimental chemotherapy in treating early-stage breast cancer, according to a groundbreaking study.
The decade-long study, discussed Sunday at the American Society of Clinical Oncology conference in Chicago, is hailed as the largest breast cancer treatment trial ever conducted. It showed most patients with an intermediate risk of cancer recurrence can avoid chemotherapy without hurting their chances of beating the disease.
That could affect up to 70,000 women a year in the USA and thousands more around the world, the study said.
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"The impact is tremendous," said the study's leader, Joseph Sparano of Montefiore Medical Center in New York. Most women in this situation don't need treatment beyond surgery and hormone therapy, and "the rest of them are receiving chemotherapy unnecessarily."
Jennifer Litton, an associate professor and oncologist at MD Anderson Cancer Center in Houston, said the results will help patients and their doctors make more informed decisions.
"Moving forward, when women are making this decision, this study will help us put it into perspective and give them better advice next week than we were able to give them last week," said Litton, who attended the conference where the results were discussed.
The study, funded by the National Cancer Institute, foundations and proceeds from the U.S. breast cancer postage stamp, is the latest development in a national trend on cancer treatments. For the past several years, cancer care has evolved away from chemotherapy — older drugs with harsh side effects — in favor of gene-targeting therapies, hormone blockers and immune system treatments. When chemo is used, it's sometimes for shorter periods or lower doses than it once was.
Another study at the conference found that Merck's immunotherapy drug Keytruda worked better than chemo as initial treatment for most people with the most common type of lung cancer, and with far fewer side effects.
The breast cancer study cast doubt on chemo's necessity in treating women in early stages of the disease where it has not spread to lymph nodes, it is hormone-positive and it is not the type that the drug Herceptin targets.
Women with early-stage breast cancer tend to have high survival rates, but their case worsens drastically if the cancer returns to other parts of the body. That has prompted many to turn to chemo to avoid the spread of the disease.
In recent years, oncologists have warned that women with early-stage breast cancer are possibly being overtreated. The trial results are the latest salvo in a heated debate over when and how to use chemotherapy in combating the spread of the disease.
Chemotherapy thwarts cancer's spread but can cause unwanted side effects such as hair loss, anxiety, depression, nausea, fatigue and heart failure.
"Oncologists have been getting much smarter about dialing back treatment so that it doesn't do more harm than good," Steven Katz, a University of Michigan researcher who examines medical decision-making, told The Washington Post. "That's important because chemo is toxic; it whacks patients out and can result in long-term job loss."
The breast cancer study gave 10,273 patients a test called Oncotype DX, which uses a biopsy sample to measure the activity of genes involved in cell growth and response to hormone therapy, to estimate the risk that a cancer will recur.
For the study, the 67% of women showing an intermediate risk of recurrence had surgery and hormone therapy, and half of them also received chemo. After nine years, 94% of both groups were still alive and about 84% were alive without signs of cancer, meaning the chemo made no difference.
Lisa Carey, a breast specialist at the University of North Carolina's Lineberger Comprehensive Cancer Center, said she would be very comfortable advising patients to skip chemo if they were like those in the study who did not benefit from it.
Litton, the MD Anderson oncologist, said doctors need to consider each case on its own merits and cautioned against ruling out chemo too quickly.
"This study gives us information on a very specific group of women with a very specific type of cancer," she said, "but it doesn't tell us chemotherapy is not effective in some cases."
Contributing: Associated Press