Only little more than half of older, high-risk women with advanced breast cancer who have had their breasts surgically removed receive radiation therapy, as recommended by clinical guidelines, according to a new study.
Although guidelines published in the late 1990s and early 2000s endorsed post-mastectomy radiation therapy in high-risk women, they appear to have had little affect on clinical practice, the researchers said.
The study was published Monday in the journal Cancer.
"When physicians are not guided by published evidence, there is the chance that patient outcomes will suffer or that patients will undergo unnecessary treatments and tests," said study co-author Dr. Shervin Shirvani, with the M.D. Anderson Cancer Center in Houston, in a statement.
The researchers used the Surveillance, Epidemiology, and End Results [SEER]-Medicare database, to find and analyze data from more than 38,000 women aged 66 and over, who were treated with mastectomies for invasive cancer between 1992 and 2005.
The researchers found three landmark studies showing the survival benefits of radiation for high-risk women published between 1997 and 1999 in the New England Journal of Medicine and The Lancet did seem to influence treatment rates. The number of post-mastectomy, high-risk women getting radiation therapy rose from 36.5 percent in 1996 to 57.7 percent in 1998, they said.
But later guidelines endorsing the radiation treatment in these women didn't seem to move the dial. From 1999 to 2005, only about 55 percent of the high-risk women received radiation therapy.
Women who were older, had smaller tumors, and whose cancers lacked lymph node involvement were less likely to get radiation therapy, the researchers said.