广泛期小细胞肺癌胸部放疗最佳剂量探析

目的 探讨与分析广泛期小细胞肺癌接受胸部放疗的最佳剂量。方法 回顾分析2010-2015年间在天津医科大学肿瘤医院诊断为广泛期小细胞肺癌患者,均接受了一线诱导化疗,选取化疗后未进展患者216例,其中接受胸部放疗180例,单纯化疗36例。依据患者剂量分布特点,折算为等效生物剂量,然后分为剂量A组(31.3~40.2 Gy,23例)、B组(46.0~46.8 Gy,38例),C组(49.5~53.7 Gy,43例)及D组(55.1~60.6 Gy,76例)。为进一步比较,分为低剂量组(31.3~46.8 Gy,61例),高剂量组(49.5~60.6 Gy,119例)。采用Kaplan-Meier法进行预后分析,Cox模型进行多因素预后分析,倾向性评分用以控制混杂变量。结果 全组患者中位生存期13.2个月,A、B、C、D、化疗组分别为8.3、11.0、15.8、17.8、8.1个月(P=0.000);A组与B、化疗组相近(P=0.172、0.495),B组与化疗组不同(P=0.020),C、D组间相近(P=0.624),C、D组与A、B、化疗组均不同(P<0.05)。全部患者中位无进展生存期为8.7个月,A、B、C、D、化疗组分别为6.5、7.6、11.8、12.4、6.1个月(P=0.000);A组与B、化疗组相近(P=0.588,P=0.668),B组与化疗组接近(P=0.070),C、D组间也相近(P=0.627),C、D组与A、B、化疗组均不同(P<0.020)。多因素分析提示转移病灶数目、胸部放疗剂量为总生存率、无进展生存率生存共有影响因素(P<0.05),而同步放化疗为总生存率的影响因素(P=0.018)。低剂量组分别与高剂量组进行倾向性评分匹配后,发现低剂量(50例)与高剂量组(50例)无论总生存、无进展生存均不同(中位生存期 10.9、17.5个月,P=0.045 ;中位无进展生存 7.4、10.7个月,P=0.014)。结论 广泛小细胞肺癌接受胸部放疗的剂量应予以较高的剂量(49.5~53.7 Gy),过低剂量(≤40.2 Gy)可能无法延长生存时间,同时过高剂量(≥55.1 Gy)也无法进一步生存获益。

Analysis of optimal dose of thoracic radiotherapy for patients with extensive stage small cell lung cancer

Objective To investigate the optimal dosage of thoracic radiotherapy in patients diagnosed with extensive stage small cell lung cancer (ES-SCLC). Methods Clinical data of ES-SCLC patients admitted to Tianjian Medical University Cancer Institute& Hospital between February 2010 and October 2015 were retrospectively analyzed. All patients received the first-line induction chemotherapy. Subsequently, 216 patients without progression after the first-line induction chemotherapy were apportioned to the thoracic radiotherapy (n=180) group and chemotherapy alone group (n=36).According to the distribution characteristics of the biological equivalent dose, all patients were assigned into the A (31.3-40.2 Gy, n=23), B (46.0-46.8 Gy, n=38), C (49.5-53.7 Gy, n=43) and D groups (55.1-60.6 Gy, n=76).For the subgroup analysis, the low (31.3-46.8 Gy, n=61) and high dose groups (49.5-60.6 Gy, n=119) were divided. Kaplan-Meier survival analysis was used for prognostic analysis. Cox’s regression model was conducted for multivariate prognostic analysis. Propensity score matching was utilized to control the confounding variables. Results The median overall survival of all patients was 13.2 months, and 8.3, 11.0, 15.8, 17.8 and 8.1 months for patients in the A, B, C, D and chemotherapy alone groups, respectively (all P=0.000).The median overall survival did not significantly differ between A and B/chemotherapy groups (P=0.172, P=0.495), and similar results were obtained between the C and D groups (P=0.624).The median overall survival in the B group was significantly longer than that in the chemotherapy alone group (P=0.020).Statistical significance was noted between C and D groups, and A and B groups (all P<0.05).The median progression-free survival for all patients was 8.7 months, and 6.5, 7.6, 11.8, 12.4 and 6.1 months in the A, B, C, D and chemotherapy alone groups, respectively (all P=0.000).The median progression-free survival did not significantly differ between A and B chemotherapy groups (P=0.588, P=0.668).The progression-free survival in the B group was slightly longer than that in the chemotherapy group without statistical significance (P=0.070).No statistical significance was observed between the C and D groups (P=0.627).Statistical significance was noted between C and D groups, and A and B groups (all P<0.02).Uni-and multi-variate analyses prompted that the number of metastatic lesions and dose of thoracic radiotherapy were the independent predictors of the overall survival and progression-free survival (both P<0.05).Concurrent chemoradiotherapy was the independent predictor of the overall survival (P=0.018).After the propensity score matching, the median overall survival and progression-free survival significantly differed between the low (n=50) and high dose groups (n=50)(10.9 vs. 17.5 months, P=0.045;7.4 vs. 10.7 months, P=0.014). Conclusions A relatively high dose ranging from 49.5 to 53.7 Gy is recommended during thoracic radiotherapy for ES-SCLC patients. An excessively low dose (≤40.2 Gy) probably fails to prolong the survival time, and an extremely high dose (≥55.1 Gy) cannot enable the patients to obtain survival benefits.