A retrospective study of 157 patients comparing platinum-anthracycline to other platinum combination for untreated unresectable thymoma: NEJ023B.
Authors: Saito Go , Ko Ryo , Shiko Yuki , Nagai Yoshiaki , Ebina-Shibuya Risa , Isobe Kazutoshi , Nishiyama Kazuhiro , Wakui Hiroshi , Takashima Yuta , Sonehara Kei , Shimamura Shoko , Kaira Kyoichi , Nakahara Yoshiro , Ashinuma Hironori , Nagashima Hiromi , Suzuki Yohei , Chubachi Kei , Maemondo Makoto , Kobayashi Kunihiko , Shukuya Takehito 
Published: July 2024

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Background: The optimal primary treatment for unresectable thymoma remains unclear to date. Methods: We enrolled patients with unresectable or recurrent thymomas that were confirmed between April 1, 2000, and March 31, 2020, and had received palliative radiotherapy and/or chemotherapy, from 38 facilities in Japan. Results: A total of 204 cases were registered, with 157 receiving platinum-based chemotherapy as first-line chemotherapy. The median age of these 157 cases was 58 years (range 24-79), with 74 females (47%). The histological types were: A in 3 (2%), AB in 13 (8%), B1 in 27 (17%), B2 in 60 (38%), B3 in 41 (26%). Out of 157 cases, 97 (62%) recurred after radical surgery or chemoradiotherapy. Of the remaining cases, 4 (3%) in Masaoka stage III, 44 (28%) in stage IVa, and 12 (8%) in stage IVb. At the start of first-line chemotherapy, 48 (31%) had paraneoplastic syndrome, and the performance status was 0 in 81 (52%). As first-line chemotherapy, platinum plus anthracycline combination was used in 104 cases (66%) (doxorubicin + cisplatin + vincristine + cyclophosphamide: ADOC in 76, cisplatin + doxorubicin + cyclophosphamide: CAP in 10), and other platinum combinations in 53 cases (34%) (carboplatin + paclitaxel in 31, cisplatin + etoposide in 11, carboplatin + nab-paclitaxel in 7). The response rates for platinum plus anthracycline and other platinum combinations were 57% and 30% (p = 0.0024), and disease control rates were 96% and 100% (p = 0.18), respectively. During a median observation period of 50.5 months (range 2.0-191.8 months), patients received a median of 2 chemotherapy regimens (range 1-9), one radiation (range 0-4), and one salvage or volume-reduction surgery (range 0-3). The median progression-free survival (PFS) was 13.4 months for platinum plus anthracycline vs. 15.0 months for other platinum combinations (hazard ratio 0.932, p = 0.72), and after propensity score matching (46 cases in each group), it was 11.7 months vs. 12.1 months (hazard ratio 1.02, p = 0.92). The median overall survival (OS) was 111.9 months for platinum plus anthracycline vs. 84 months for other platinum combinations (hazard ratio: 0.733, p = 0.23), and after propensity score matching (46 cases in each group), it was 113.5 months vs. 93.8 months (hazard ratio: 0.711, p = 0.34). Of the 157 cases, 67 deaths were observed, with the causes being progression of the primary disease in 47, infections in 9, and cardiac diseases in 4. Conclusions: Platinum plus anthracycline showed better response rates than other platinum combinations as a first-line chemotherapy, but there was no significant difference in PFS and OS. The median PFS for primary treatment was about one year, whereas the overall survival was nearly ten years, indicating the need for long-term multidisciplinary approach. Clinical trial information: UMIN000048181.