Decisions regarding adjuvant therapy should take into account a woman’s risk of disease recurrence, her life expectancy, the benefits and risks of each treatment, and her preferences. Adjuvant tamoxifen clearly reduces the risk of recurrence and death in older women, although the benefits are limited to women with hormone receptor-positive tumors. Five years of tamoxifen has a favorable side effect profile and should be considered for all older women with hormone receptor-positive tumors. Adjuvant chemotherapy appears to reduce the risk of recurrence and death in women under the age of 70. To date, there is not enough information about women age 70 and older to make definitive conclusions regarding the benefits of chemotherapy in this population. Chemotherapy should be considered in this age group if the tumor is hormone receptor negative or in the setting of a high risk of disease recurrence. In 1998, a panel of experts at the St. Gallen Breast Cancer Conference made recommendations for adjuvant therapy for women older than 70 years (

Table 33.11).

In addition to disease characteristics as outlined in the aforementioned recommendations, concern regarding toxicity of therapy, comorbidities, and life expectancy will weigh heavily on a decision to treat an elderly woman with adjuvant chemotherapy.

Extermann and colleagues used a Markov model to determine the threshold risk of relapse for which women up to age 85 with or without comorbidity would derive benefit from adjuvant therapy. For healthy women at age 65, the threshold risk of relapse was 11% for a 1% benefit in 10-year survival from tamoxifen. This threshold increased to 20% for women age 65 with significant comorbidity. For healthy women age 85, the threshold risk of relapse was 28% for a 1% benefit in 5-year survival, increasing to 35% for sicker women in the same age group. Of note, no 10-year survival benefit was seen in the older age group. For chemotherapy, the threshold risk for a 1% benefit rose from 19% in a healthy 65-year-old to 62% in a sick 85-year-old. This model was sensitive to quality of life as well, a major consideration because of the relatively small impact of adjuvant therapy on survival in older women.

Future studies of adjuvant therapy should be designed to include more elderly women. These studies should measure quality of life as well as traditional endpoints. With its toxicities and modest benefits even in younger women, it is unlikely that adjuvant cytotoxic chemotherapy will ever be used extensively in women over age 70. Studies examining the benefits of new hormonal agents and other less toxic drugs, including trastuzumab, hold promise for the future adjuvant treatment in women of all age groups, including those age 70 or older.