Many older women with early breast cancer can safely skip radiation after having a lump removed, two studies suggest.
Most women should still undergo radiation, because it helps prevent relapses within the same breast, the researchers say. But breast cancer grows so slowly in older women — at least those over 70 — that many could forgo those treatments with little risk of a relapse.
“This is a very reasonable option for these women, and they have to weigh the risks and benefits with their physician,” said Dr. Kevin Hughes, a cancer surgeon at Massachusetts General Hospital and lead researcher in one of the two studies reported Thursday in The New England Journal of Medicine.
In view of the findings, some doctors suggested that up to 40,000 women a year in the United States might consider skipping radiation.
Many early tumors today are treated by lumpectomy, in which the lump instead of the entire breast is removed. The drug tamoxifen is also widely given to prevent the spread of cancer. Doctors also give radiation to most patients just to be safe, though research shows that the vast majority will not suffer a relapse anyway.
“We know that most women with these small tumors don’t need radiotherapy, but the problem is identifying them,” said Dr. Ian Smith of Royal Marsden Hospital in London, who wrote an accompanying editorial.
In their five-year studies, both research teams compared early-cancer lumpectomy patients on tamoxifen with and without radiation. A Canadian team looked at 769 women ages 50 and older. The American group, led by Hughes and backed by the National Cancer Institute, focused on 636 women 70 and older.
To the researchers’ disappointment, the Canadian study found that without radiation, almost 8 percent suffered a relapse within the same breast. With the treatments, it was less than 1 percent.
“The majority of women benefit from radiation, and the magnitude of the benefit is enough to warrant the small side effects,” said researcher Dr. Anthony Fyles, at Princess Margaret Hospital in Toronto.
Still, there was no difference in the risk of cancer spreading elsewhere in the body. And the relapse rate within the same breast in both patient groups combined was noticeably lower for women over 60 than for women in their 50s — 3.5 percent compared with 6 percent.
Side effects difficult for older women
In the American study, 1 percent of women ages 70 or over had a relapse within the same breast with radiation, and just 4 percent without it — a very slight risk, in the eyes of the researchers.
Relapses in which the cancer has not spread to other parts of the body are usually not catastrophic. Most can be effectively treated with more surgery. In fact, patients without radiation lived just as long on average as the other women in both studies — despite their higher rates of relapse.
The typical five-to-six-week U.S. regimen — with side effects like breast pain, redness, swelling and fatigue — can be trying for some women, especially older ones. The treatments can cost $15,000 in the United States, and perhaps less than half that in Canada.
However, Monica Morrow, a cancer surgeon at Fox Chase Cancer Center in Philadelphia, suspects that fewer than 40,000 patients will prove to be good candidates.
“The person who is terrified of dying of cancer wants to do everything they can to prevent cancer from coming back,” she said.