Breast cancer may not change lifespan for older women

2011-03-15

Older women who are diagnosed with early-stage breast cancer can expect to live just as long as peers without breast cancer, according to a new study.

That’s “a very encouraging message,” said Dr. Elena Elkin, a breast cancer researcher at Memorial Sloan-Kettering Cancer Center who was not involved with the study. “More of the breast cancers we find are very small and diagnosed at an early stage. For older women especially these cancers generally have a favorable diagnosis,” she told Reuters Health.

More than 200,000 women are diagnosed with breast cancer each year in the U.S., and a woman’s risk of getting the disease increases as she gets older.

There is ongoing debate in the medical community, however, over whether routine screening for certain cancers will actually extend lives, particularly in older people whose life expectancy is likely to be influenced by other health issues, such as heart disease.

In the current study, researchers compared the life expectancy and causes of death in women age 67 and older who were diagnosed with breast cancer and in a similar group of women without breast cancer.

By consulting a register of cancer diagnoses in Medicare patients, the authors, led by Dr. Mara Schonberg of the Beth Israel Deaconess Medical Center in Brookline, Massachusetts, were able to identify almost 65,000 older women who were diagnosed with breast cancer of any stage between 1992 and 2003. For comparison, they collected information for a group of about 170,000 women of similar age, also on Medicare, who were not diagnosed with breast cancer.

The researchers tracked women in both groups through 2006 – close to 8 years of follow-up on average – to determine how many of them died, and from what cause.

Women diagnosed with ductal carcinoma in situ (DCIS) – the earliest stage of breast cancer – and stage I cancer were just as likely to survive through the end of the study period as women who were never diagnosed with cancer.

Women under 80 who were diagnosed with DCIS were actually slightly more likely to survive for at least 5 years than women who were not diagnosed with breast cancer. That could be because of the “healthy user effect,” the authors say – women who are diagnosed with breast cancer are more likely to have been screened for cancer than women who aren’t diagnosed, and may also be more health-conscious in other ways.

Women with stage I breast cancer and those over 80 with DCIS had the same rate of survival over the course of the study as women without breast cancer.

In women under 80 years old, 89 percent survived 5 years after a diagnosis of DCIS and 87 percent after being diagnosed with stage I cancer. In women age 80 and older, 70 percent were still alive 5 years after being diagnosed with DCIS, compared to 66 percent who were diagnosed with stage I breast cancer.

Between 6 and 18 percent of women with early stage cancer that died within 5 years died from breast cancer. Heart disease was the most common cause of death for women with early stage breast cancer.

Survival chances were higher in women with early-stage breast cancer when they had a mastectomy or breast-conserving surgery and radiation together, rather than when they just had breast-conserving surgery or had no surgery at all.

When older women were diagnosed with stage II or higher breast cancer, they did not survive as long as the non-cancer group. A stage II diagnosis, for example, meant women were 1.5 times less likely to survive the study period than women without breast cancer, and a stage III diagnosis meant they were three times less likely to survive.

The findings, the authors say, suggest that doctors should be talking with older women about the risks and benefits of being screened for breast cancer. Screening might pick up an early stage cancer that is advancing – in which case treatment could prevent the cancer from becoming worse.

In some cases, however, screening might pick up cancers that would not end up cutting a woman’s life short, especially if she was at risk of dying from another condition, such as heart disease. In that sense, a woman is at risk of being treated with invasive procedures unnecessarily since they would not extend her expected lifespan.

“I suspect that a lot of these cancers are cancers that never would have affected someone’s life expectancy” had they not been caught, Schonberg told Reuters Health. However, she said, it’s very hard to know which cancers are going to progress and which are not likely to cause a woman’s death.

“This is the fundamental problem in screening for cancer in general,” Elkin added. She said that each woman’s decision about whether or not to get screened should depend on how much she would benefit from doctors catching an early-stage cancer. Every older woman “should not just get a mammogram routinely, but have a discussion with her doctor,” she said.

The main message is that “screening can be effective even in older women,” Elkin said. “What’s important is not necessarily a woman’s age but her general health and her life expectancy … and that’s true for any age.”