Older women with breast cancer are being denied lifesaving treatment and access to new, promising experimental treatments according to a new study. Writing in the journal Cancer, researchers from the Ohio State University Medical Center say women over 50 are 6 to 62 times more likely not to receive chemotherapy treatment even after controlling for identified age-related confounding and modifying factors.

"The main result suggests possible age bias in treatment of older women with adjuvant therapy," conclude the authors. However, they caution that "this finding requires confirmation as prior studies suggest that clinical considerations such as risk of metastases, treatment efficacy, and co-morbidity, as opposed to age per se, influence adjuvant treatment decisions in older women."

Studies have shown that older women are less likely to receive standard care than younger women. Hypotheses include that the benefits of adjuvant chemotherapy decline with age; the risk of drug toxicity outweighs the benefits of treatment; the risk of dying from other coexisting medical conditions may be greater than the risk of dying from cancer; and the decision to treat is based solely on chronological age - i.e., age bias.

The authors investigated 480 women with nonmetastatic breast cancer to "illuminate the true relationship between age and chemotherapy treatment by controlling for factors that alter this relationship."

First, variables were identified related to both age and chemotherapy treatment, called confounders, and variables that had a significant interaction with age, called effect modifiers. Surprisingly, baseline factors such as the presence of other medical conditions, the type of surgery, and hormone treatment were found to have had no relationship with age. Tumor stage and size, lymph node involvement, and progesterone receptor status were identified as confounders, and estrogen receptor (ER) status was identified as a modifier.

Second, the authors adjusted for these confounders and modifiers and found that chronological age by itself plays a significant role in determining treatment for women 50 and older. Compared to women under 50, women between 50 and 65 with ER positive tumors were six times more likely not to receive adjuvant chemotherapy. Meanwhile, women over 65 were 62 times more likely not to receive chemotherapy. Women over 65 with ER negative tumors were almost seven times more likely not to receive chemotherapy compared to younger women.

"This result was unexpected and contrary to our hypothesis," wrote the authors. Given the control for confounding and modifying factors, "it raises the possibility of age bias influencing the decision to treat older women with adjuvant chemotherapy."

SOURCE:
Cancer, September 15, 2003