[Analysis of tumor regression after concurrent radiochemotherapy for locally advanced hypopharyngeal carcinoma]

Objective: To investigate the pathological characteristics of tumor regression and the expression level of chemoradiotherapy resistance-related molecular markers after preoperative concurrent radiochemotherapy in patients with locally advanced hypopharyngeal carcinoma. Methods: The clinical data of 44 patients with locally advanced hypopharyngeal carcinoma who underwent preoperative concurrent radiochemotherapy in the Department of Head and Neck Surgery of Shandong Otolaryngology Hospital from August 2016 to August 2020 were retrospectively analyzed. All patients received preoperative concurrent chemotherapy and radiotherapy. After radiochemotherapy, electronic laryngoscopy and imaging examination were performed to assess the tumor regression status. After 4 weeks, surgical resection was performed, and the specimens of the primary focus were processed as continuous pathological sections. After operation, HE staining and TdT-mediated dUTP nick-end labeling (TUNEL) method were used to detect the distribution characteristics and apoptosis of the remaining cancer focus, and immunohistochemistry was performed to determine the proliferation of the remaining cancer focus and the expression of radiation resistance-related molecular markers [signal transducer and activator of transcription 3 (STAT3), hypoxia-inducible factor-1alpha (HIF-1α), sex determining region Y-box 2 (SOX2), and P53]. Results: A total of 44 patients were included, all of whom were male, with a mean age of (58.3±3.5) years. There were 40 cases of pyriform sinus carcinoma and 4 cases of posterior pharyngeal wall carcinoma. Twenty-nine cases were in stage T3 and 15 cases were in stage T4. There were 6 stage Ⅲ cases and 38 stage Ⅳ cases. According to the response evaluation criteria in solid tumors (RECIST), 13 patients achieved complete response (CR), 22 patients had partial response (PR), and 9 patients achieved stable disease (SD) after concurrent radiochemotherapy. The primary lesion resection methods included 19 cases of hypopharyngeal circumferential resection and 2 cases of total laryngectomy and partial hypopharyngeal resection. Twenty-three cases underwent supracricoid cartilage subtotal laryngectomy cricoid tongue fixation (CHP). Among 22 patients with PR, 10 had large PR (remission rate ≥70%) and 12 had small PR (remission rate <70%). The residual tumor was found in 30 patients (68.2%) after resection of all primary lesions by HE staining of pathological sections, of which 3 patients (3/13) with CR had residual cancer, all of which were focal residues. In large PR patients, residual cancer was detected in 6 cases (6/10), scattered in 4 cases, and focal residual in 2 cases, respectively. Large residual tumors were detected in small PR and SD patients. TUNEL method did not show any sign of apoptosis in 30 specimens with residual cancer focus, and the positive expression rate of Ki-67 was less than 10%. The expression of STAT3 (3.40±2.49 vs 5.23±3.02, t=-2.932, P=0.007) in 19 cases (63.3%) and HIF-1α (3.73±2.66 vs 6.97±3.05, t=-4.45, P<0.001) in 22 cases (73.3%) of residual cancer were significantly higher than those before radiochemotherapy. Other molecular markers showed no significant changes. All patients were followed up for 3 years. The 2-year survival rate was 59.3%, and the 3-year survival rate was 54.1%. Conclusions: Preoperative radiochemotherapy can make some patients with locally advanced hypopharyngeal carcinoma achieve complete or significant remission in clinical evaluation, but pathological detection still shows some residual cancer lesions with enhanced anti-apoptosis ability and decreased proliferation activity.