A study published in the Journal of the American Geriatrics Society found that older women with breast cancer have a poor response to chemotherapy, while older patients with advanced colon cancer (both men and women) did well.
A retrospective evaluation of trial outcomes in older breast cancer patients discovered that older women with breast cancer have a poor response to chemotherapy—treatment with doxorubicin and cyclophosphamide (DC) being an exception. However, older patients with advanced colon cancer (both men and women) responded well to chemotherapy, the researchers found.
The study, published in the Journal of the American Geriatrics Society, analyzed data from 16 Surveillance, Epidemiology, and End Results (SEER) areas from the SEER-Medicare linked database. More than 14,000 women with Stage I to IIIa hormone receptor—negative breast cancer and nearly 27,000 men and women with Stage III colon cancer. All participants were diagnosed between 1992 and 2009 and were at least 65 years old. The authors evaluated mortality as the primary outcome and chemotherapy treatment was the main exposure.
The best responders to chemotherapy among the breast cancer patients were women 65 to 69 years of age; their risk of all-cause mortality was significantly lower than among those who did not receive chemotherapy in the entire cohort and in a propensity-matched cohort. A similar pattern was observed in older age groups—those 70 to 74 years old and 75 to 70 years old. However, women older than 80 years, unless they had received DC, were no longer in the lower-risk group for mortality.
A different scenario was observed among older colon cancer patients with advanced disease (Stage III). Chemotherapy was effective in all ages from 65 to 84 years in Stage III colon cancer patients; those among older patients, for example those in the 85 to 9 years old, the risk of mortality was significantly lowered following chemotherapy.
“Previous clinical trial research has shown that chemotherapy is inefficient for breast cancer patients over the age of 70, but the trials have been considered to have small sample sizes. This study, using large sample sizes, shows that there's strong evidence to this finding,” said Xianglin Du, MD, PhD, lead author of the study.
The authors suggest several mechanisms for the observed outcomes of declining responsiveness with age, including declining sensitivity of tumors to chemotherapy that may be dependent on hormone-dependent disease (breast cancer) but which may not affect non-hormonal diseases (colon cancer). While DC seemed effective even in older patients with breast cancer, the authors explain that cardiotoxicity is a major concern with DC and so older adults may not receive the combination as often but would rather be treated with less-effective chemotherapy regimens.
The results of this retrospective analysis highlight the importance of utilizing evidence-based guidance in treating the geriatric population. This would ensure improved quality of life and also avoid potentially inappropriate treatment regimens.