A case report: Achieving complete response in synchronous primary lung and tongue squamous cell carcinomas through the integration of albumin-bound paclitaxel, cisplatin, and tislelizumab.

With advances in medical technology, the diagnosis of multiple primary cancers (MPC) is becoming increasingly common. Despite significant advancements in therapeutic approaches, definitive management strategies for synchronous primary cancers are still not fully established. We report the case of a 56-year-old male smoker diagnosed with synchronous primary lung (cT2N0M0, stage IB) and base-of-tongue (cT1N2M0, stage IVA) squamous cell carcinoma (SCC), exhibiting a high PD-L1 tumor proportion score (TPS) of 90%. After multidisciplinary team evaluation, the patient received induction chemoimmunotherapy with albumin-bound paclitaxel, cisplatin, and the PD-1 inhibitor tislelizumab. Following four cycles, imaging assessments indicated a partial response (PR) in both malignancies according to RECIST 1.1. Subsequent thoracoscopic resection of the lung lesion confirmed a pathological complete response (pCR; ypT0N0). Remarkably, the base-of-tongue primary also achieved a clinical complete response (cCR), obviating the need for surgical or radiotherapeutic intervention. The patient continued to adjuvant tislelizumab. At the last follow-up in August 2025, the patient had a progression-free survival (PFS) of 29.8 months, with no evidence of recurrence in the lung lesions. This case demonstrates the efficacy of a multimodal induction chemoimmunotherapy in achieving complete response and preserving organ function, thereby providing a promising therapeutic option for patients with synchronous lung and base-of-tongue SCC.