The effect of the time between diagnosis and treatment, and the delay in adjuvant therapy on progression-free survival and overall survival in patients receiving adjuvant chemotherapy due to breast cancer or colon cancer

Breast cancer is the most common cancer among women worldwide and ranks second in cancer-related deaths among women. There are numerous studies on breast cancer both globally and in our country. In this study, we aimed to evaluate the effect of the time between diagnosis and treatment and the delay in adjuvant chemotherapy on progression-free survival and overall survival in patients receiving adjuvant chemotherapy due to breast cancer. Since our clinic mainly provides neoadjuvant treatment for colon cancer, we did not include those patients. A retrospective review was conducted on 2000 patients diagnosed with breast cancer in the Medical Oncology Department of Hacettepe University between 2015 and 2022. The data of 558 patients who received adjuvant treatment were recorded and analyzed. The average age of diagnosis was found to be 49.3 ± 10.4 years. In terms of pathological diagnoses, 84.1% were IDC, 6.1% were ILC, and 9.9% were mixed IDLC. It was observed that 84.2% of the patients underwent MRM. After an average follow-up period of 62.00 ± 28 months, 5.2% of the patients showed progression. Among 294 patients who experienced delays between chemotherapy cycles, the average delay between cycles was 4.69 ± 6.31 days. A significant difference was found between the variables of the average delay between chemotherapy cycles, daily delay duration, and the reason for delay, and the occurrence of progression. The most common delays were due to patient-related reasons and delays related to NPA. It was observed that patients received chemotherapy an average of 24.07 ± 12.62 (2-94) days after surgery. A significant difference was found between every 10-day delay and the occurrence of progression. It was found that the histological subtype (HR+), early-stage disease, early initiation of chemotherapy after surgery, and the absence of delay in adjuvant chemotherapy cycles had a positive impact on progression-free survival. There is a need for multi-center studies involving more patients to obtain clearer information on this subject.