Clinical outcomes in elderly rectal cancer patients treated with neoadjuvant chemoradiotherapy: impact of tumor regression grade Tumor regression grade after neoadjuvant chemoradiotherapy in elderly rectal cancer patients

Purpose: The effect of neoadjuvant chemoradiotherapy (CRT) and the relationship between pathological complete response (pCR) with clinical outcomes has been evaluated in elderly locally advanced rectal cancer (LARC) patients. Methods: We retrospectively analyzed 117 LARC patients treated with conformal RT and concomitant fluoropirimidine-based chemotherapy. A dose of 4500 cGy, on the pelvis, up to 5500 cGy on the tumor was delivered. Multidisciplinary evaluation, including geriatric assessment, was previously performed to identify frail patients unsuitable for combined treatment. Results: The median age was 75 (range 70–88 years), and 103 (88%) patients had ECOG Performance Status (PS) = 0. All patients except one completed CRT. Ten (8.5%) patients temporarily suspended CRT for acute severe hematologic complication, diarrhea and/or proctitis and hypokalemia. Of the 103 operated patients (88%), a pCR, according to Mandard tumor regression grade (TRG) score, was obtained in 28 patients (27.2%), with TRG1-2 rate of 43.7%. The 3- and 5-year overall survival (OS) rates were 80.2% ± 4.2% and 68.0% ± 5.2%, 72.4% ± 4.5% and 57.8% ± 5.2% for disease-free survival (DFS), and 92.2% ± 2.8% and 89.5% ± 3.9% for loco-regional control. Patients with TRG1-2 had 3- and 5-year OS rates of 84.1% ± 6.6% and 84.1% ± 6.6% compared with 82.8% ± 5.5% and 67.7% ± 7.2% for patients with TRG3-5 (p = 0.012). The 3- and 5-year DFS rates for patients with TRG1-2 were 77.6% ± 7.0% and 74.2% ± 7.5% compared with 70.9% ± 6.3% and 54.7% ± 7.3% for patients with TRG3-5 (p = 0.009). Conclusion: Our results reported good tolerability and clinical outcomes of neoadjuvant CRT, with a benefit in patients ≥ 70 years, confirming the prognostic role of pCR on clinical outcomes.