Dr.Seife, Edom(consultant oncologist, Assistance Professor of Medicine, AAU)Dr. Kantelhardt, Eva JohannaTafesse, Ephrem2021-01-212023-11-052021-01-212023-11-052020-09http://etd.aau.edu.et/handle/123456789/24768Introduction – Nearly more than half of post mastectomy patient needs adjuvant radiotherapy. Adjuvant radiotherapy should be given according to clinical recommended indication, dose and time to reduce risk of loco-regional tumor recurrence. Most post mastectomy patients do not get adjuvant radiotherapy due to long radiotherapy waiting time at the centers. Delayed initiation of adjuvant radiotherapy associated with increased risk of tumor recurrence. Radiotherapy waiting time at TASH oncology center is unknown and expected to be more than a year. All high risk post mastectomypatients will be registered and wait for adjuvant radiotherapy. Benefit of giving delayed adjuvant chest wall irradiation is unknown. Despite our routine clinical practice, such treatment delay should be evaluated. Objective – The main objective of study was to assess the clinical benefit of delayed adjuvant radiotherapy delivery after 1 year of post mastectomy. Methods – Institutional based retrospective cross-sectional used to assess tumor control rate among post mastectomy breast cancer patients registered at TASH radiotherapy center for the indication of adjuvant chest wall irradiation. Result- In 2016 at TASH radiotherapy center, total of 274 high risk post mastectomy patients had registered for adjuvant chest wall irradiation. At 1year of post mastectomy, among radiotherapy registered 67.5%(185) patients had stable disease. Nearly 38.6% (106)patients did not take adjuvant radiotherapy and 28.8% (79) patients had took sequentially adjuvant chemotherapy and radiotherapy. The mean radiotherapy waiting time was 8.8±1.4months .Among those who took delayed adjuvant radiotherapy, the mean post mastectomy adjuvant radiotherapy delivery time was 10.4 ±1.9 months. At 4 years follow up,62.7%(116) patients are alive, 27.6%(52) had died and 9.7%(17) had unknown status. Tumor recurrenceconfirmed in 28.6% (53) patients. Among sub-groups, 34.1% (27) and 24.5% (26) patients had tumor recurrence among those who took and did not tookdelayed adjuvant radiotherapy respectively. Adjuvant radiotherapy was not found to be association with tumor control (COR=1.5, 95% CI=0.83-3.03, P-0.16). On multivariate analysis only advanced nodal tumor showed statically significant for tumor recurrence. N2 and N3 stage patients were found to be 3.8 and 4.3 times morelikely to develop recurrence as compared to Nx& N1 patients respectively (AOR, 3.86, CI 1.72-8.65, AOR 4.34, CI 1.54-12.26) Conclusion- Delayed adjuvant radiotherapy after median 10.4 months of post mastectomy did not associate with improved tumor control. According to our finding, most unnecessary delivery of delayed adjuvant radiotherapy can be omitted and delayed adjuvant chest wall irradiation should be given among patients having one of those poor prognostic factors age less than 55 years or advanced nodal tumor disease (N2 and N3). Recommendations– Radiotherapy waiting time at TASH oncology center can be improved through avoiding unnecessary delayed radiotherapy delivery among breast cancer patients. since TASH oncology center is the only center having single cobalt-60 machines for the whole country, the available energy source should be used effectively and efficiently without compromising treatment quality.en-USWaiting time, delayed adjuvant radiotherapy, Post mastectomy patients.Thesis