Timing of adjuvant chemotherapy after surgery

This study examined whether the timing of adjuvant chemotherapy affects survival among women with breast cancer.

Surgical resection to remove all cancerous tissue is the standard of care for the treatment of breast cancer. After surgery, many patients also undergo adjuvant treatments (additional therapy following surgery), such as chemotherapy. Adjuvant chemotherapy has been shown to reduce the rate of cancer recurrence and benefit survival. However, the optimal timing following surgery to initiate adjuvant chemotherapy is still unclear. One recent analysis has suggested that for every 4 weeks delay in chemotherapy, the risk of cancer mortality is increased by 6%, however additional studies have shown inconclusive results. The current study examined whether a delay between surgery and adjuvant chemotherapy affected survival among different subtypes of breast cancer.

6,827 patient records were analyzed in this study. All patients were diagnosed with stage 1 – 3 breast cancer and treated with surgery and adjuvant chemotherapy. Data regarding breast cancer subtype, timing of chemotherapy, lymph node involvement and additional therapies received was analyzed, and their affects on overall survival and relapse-free survival (the time between treatments and until disease recurrence) were determined. 39.8% of patients underwent chemotherapy within 30 days of surgery, 43.8% within 31 to 60 days, and 16.4% started adjuvant chemotherapy 61 days or more following surgery.

Overall, among all patients waiting 61 days or more for adjuvant chemotherapy, a 19% increase in the risk of mortality was observed compared to patients who began chemotherapy within 30 days of surgery. This increased risk was most substantial among stage 3 breast cancer patients, where waiting 61 days or more for adjuvant chemotherapy increased the risk of mortality by 76% and the risk of metastatic recurrence by 36%, compared to patients initiating chemotherapy within 30 days of surgery.

When analyzing results according to breast cancer sub-type, patients with HER2-positive (human epidermal growth factor receptor 2 dependent) breast cancer were found to be most affected by treatment delay. Among HER2-positive breast cancer patients, waiting 61 days or more for adjuvant chemotherapy more than tripled the risk of mortality compared to patients who waited 30 days or less. Among triple negative (not expressing any receptors such as estrogen, progesterone or HER2) breast cancer patients, a 54% increase in the risk of mortality was noted with adjuvant chemotherapy delay of 61 days or more. Among hormone receptor-positive (estrogen or progesterone dependent) breast cancer patients, delayed adjuvant chemotherapy exhibited the least harmful effect, increasing the risk of mortality by 29% and the risk of cancer recurrence by 14%.

This analysis concluded that delaying adjuvant chemotherapy significantly impacts survival and the risk of recurrence among breast cancer patients.