Breast cancer in old age has a different profile from breast cancer in middle age and treatment tends to be different also. We define "old age" for purposes of this article as over 70, with apologies to the young old who do not view themselves as elderly, and in fact, may be healthier and more vigorous than many people in their sixties. Approximately 24% of breast cancers in the U.S. are diagnosed in women aged 70 to 84 years.

Treatment choices are influenced by the fact that breast cancer can be less aggressive in old age (and therefore might not require aggressive treatment), and that some old women might not be able to tolerate certain treatments because of pre-existing medical conditions or frailty. Based on the available evidence, these perceptions can lead to undertreatment of some women who could benefit from it. Old women can also find themselves undergoing unnecessary procedures, for example axillary node dissection in women with small tumors who are not going to receive chemotherapy in any event and will not benefit from the additional staging information the procedure might provide.

Characteristics of breast cancer in older women

The biological characteristics of breast cancer appear to change with age. Estrogen receptor (ER) and HER2 expression tends to increase with advancing age, while proliferation markers decline. This pattern is consistent with reduced aggressiveness of the disease with advancing age. On the other hand, old women are more likely to have tumors in both breasts (bilateral breast cancer) than middle aged women. This makes sense since their breasts have had more time to develop tumors and the factors contributing to tumor growth in one breast are for the most part also present in the other. This has led some observors to conclude that contralateral breast screening with breast MRIs should be considered in older women with newly diagnosed breast cancer.

While most tumors in elderly women are indolent, aggressive breast cancer still does occur. One survey of U.S. Medicare patients found that approximately 18% of elderly metastatic breast cancer patients had triple negative (ER-/PR-/HER2-) tumors. Aggressive breast cancer such as triple negative disease may be less common, but when it does it occur, it can be just as deadly. Also, breast cancer is more likely to recurr in women over 70 than younger women. Therefore, treatment plans should be based on the specific characteristics of the disease of each patient and her overall health.

Women in families with harmful BRCA1 or BRCA2 mutations continue to have increasing risks of breast and ovarian cancer in their seventies. This implies that intensive breast screening of BRCA carriers should continue even after age 70. Even normal risk women can benefit from continued mammograms after age 75, according to one study. Women over 75 who were diagnosed with breast cancer based on mammograms that took place more than two to five years since the last mammogram had less favorable breast cancer characteristics and increased rates of breast cancer-specific death compared to women who had been screened within the past two years.

Treatment of breast cancer in older women

Treatment of breast cancer in old women often varies from the standard of care. This makes sense for women who are too ill or frail to benefit from treatment. However, there are troubling reports that old women with low income receive less, whereas elderly married women receive more, of the treatment that would normally be considered appropriate, even taking account ill health and tumor characteristics. One 2012 study reported that increasing age was associated with higher breast cancer-specific mortality among postmenopausal women with ER+/PR+ breast cancer.

While most old women diagnosed with breast cancer will have surgery to remove the tumor if at all possible, radiotherapy is sometimes omitted and chemotherapy is often omitted. For the fortunate majority who have very small or slow-growing tumors, such omissions might not reduce life span. One study reported that older women with hormone receptor positive breast cancer who were unable or unwilling to undergo surgery were treated successfully with the aromatase inhibitor Femara. On the other hand, an otherwise healthy woman in her seventies (who might expect to live an additional 20 years) who is diagnosed with breast cancer that could easily metastasize within three years might benefit from appropriate radiation and chemotherapy, as would be offered to a middle aged woman.

Below are links to recent studies on breast cancer in old age. For a more complete list of studies, please click on the tag old age.