Differences between lung adenocarcinoma and squamous cell carcinoma in histological distribution of residual tumor after induction chemoradiotherapy

Hiroaki Nomori,Hiroshi Sugimura,Atsushi Shiraishi,Ayumu Otsuki,Kazufusa Shoji,Yu Oyama,Yue Cong,Koichi Honma

doi:10.1007/s12672-021-00431-8

Hiroaki Nomori, Hiroshi Sugimura + Show 6 more

Open Access

https://doi.org/10.1007/s12672-021-00431-8

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Abstract

AimsTo facilitate dose planning for convergent beam radiotherapy in non-small cell lung cancer (NSCLC), tumor response and histological distribution of residual tumors after induction chemoradiotherapy (ICRT) were compared between adenocarcinoma (AD) and squamous cell carcinoma (SQ).MethodsNinety-five patients with N1–2 or T3–4 NSCLC were treated with ICRT followed by surgery; 55 had AD and 40 had SQ. For the evaluation of distribution of residual tumors, the location of the external margin of residual tumors was assessed on surgical materials as follows: radius of whole tumor (“a”); distance between the center of tumor and the external margin of residual tumor (“b”); and its location (“b/a”).ResultsOf the 55 AD cases, 8 (15%) showed pathological complete remission, which was significantly less frequent than 22 of 40 SQ cases (55%) (p < 0.001). AD showed the residual tumors at the most periphery of tumor (b/a = 1.0) more frequently than SQ, i.e., 39/55 (71%) versus 6/40 (15%), respectively (p < 0.001). Even in 65 cases other than the pathological complete remission, external margins in 47 AD cases located more periphery than those in 18 SQ cases, of which mean b/a values were 0.97 ± 0.17 and 0.70 ± 0.29, respectively (p < 0.001).ConclusionAD showed worse tumor response to ICRT than SQ. After ICRT, AD remained at the periphery of primary tumor more frequently than SQ. It seems that, also in the convergent beam radiotherapy, the periphery part of AD would be more resistant than that of SQ.

Highlights

Radiotherapy is an important treatment modality for lung cancer, of which ultimate goal is to achieve local tumor control while sparing the surrounding normal tissue to limit toxicities
The elucidation of the distribution of radiosensitivity within a primary site of non-small cell lung cancer (NSCLC) currently depends on examination of the distribution of residual tumors on surgical materials after induction chemoradiotherapy (ICRT) [4,5,6,7,8], which has been frequently used for locally advanced NSCLC
Of the 107 patients treated with ICRT, surgery was not performed in 10 patients

Summary

Introduction

Radiotherapy is an important treatment modality for lung cancer, of which ultimate goal is to achieve local tumor control while sparing the surrounding normal tissue to limit toxicities. While a stereotactic radiotherapy has been used as a convergent beam therapy for non-small cell lung cancer (NSCLC), an intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) is recently used to adjust a radiation dose distribution (i.e., dose painting) around the tumor to decrease damage of surrounding normal tissue [1, 2]. The IMRT and VMAT adjust the radiation dose only around tumor but not within it, because the distribution of radiosensitivity within a tumor has not been clarified, which could cause local recurrence. To clarify the distribution of radiosensitivity within a tumor, a pathological examination of tumors treated by radiotherapy is necessary, preoperative radiotherapy is rarely conducted these days. While two studies evaluated the difference in tumor responses after ICRT between adenocarcinoma (AD) and squamous cell carcinoma (SQ) [9, 10], no reports have examined the differences in residual tumor locations after ICRT

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