Purpose To evaluate the mutagen sensitivity phenotype on the risk of second primary cancer (SPC) in patients with head and neck squamous cell carcinoma (HNSCC), and to estimate the long-term rate of SPC and the outcome with SPC. Methods A survey was made regarding SPC among 124 younger (≤ 50 years) adults with HNSCC who were enrolled in a pretreatment mutagen sensitivity investigation during 1996–2006. Mutagen sensitivity was assessed by exposing lymphocytes to bleomycin in vitro and quantifying the bleomycin-induced chromatid breaks per cell (b/c). Patients were classified as hypersensitive (> 1 b/c) or not hypersensitive (≤ 1 b/c). Results Mean follow-up time for all patients was 68 months (range: 5–288 months), and the 15-year cancer-specific survival was 15%. Twenty patients (16%) developed a SPC (15-year estimated rate: 41%), and half of them was hypersensitive. The crude rate of SPC for hypersensitive (n = 65) or not hypersensitive (n = 59) patients were 15 and 17%, respectively (p = 0.4272). The 15-year estimated rate of SPC for hypersensitive and not hypersensitive patients was 36 and 48%, respectively (p = 0.3743). Gender, UICC stages, anatomical sites of index cancer did not prove to be a significant risk factor for SPC. Forty-five percent of SPC developed after the 10-year follow-up. The 3‑year cancer-specific survival was 23% with SPC. Conclusion According to our findings, mutagen hypersensitivity was not associated with an increased SPC risk in HNSCC patients. Patients are at a lifelong risk of developing a SPC. Survival with SPC is very poor.

Background: Oral or laryngeal leukoplakia has an increased risk for malignant transformation but the risk of the two anatomical sites has not been compared to each other yet. Materials and Methods: Clinical data of 253 patients with leukoplakia (oral = 221 or laryngeal = 32) enrolled from January 1996 to January 2021 were analyzed. One hundred and seventy underwent biopsy and 83 did not. The mean follow-up time was 148.8 months. Risk factors for the malignant transformation of leukoplakia were identified using Cox proportional hazard models. Results: In the oral or laryngeal group, the rate of cancer was 21.7% and 50% (p = 0.002), respectively. The 10-year estimated malignant transformation was 15.1% and 42% (p < 0.0001), respectively. The laryngeal group had an increased risk of malignant transformation (p < 0.0001). The 5-year estimated survival with leukoplakia-associated cancer for the oral or laryngeal group was 40.9% and 61.1% (p = 0.337), respectively. Independent predictors of malignant transformation in the oral group were dysplasia and the grade of dysplasia of the leukoplakia, and in the laryngeal group, dysplasia had a significant impact. The malignant transformation rate was low for oral patients without biopsy or with no dysplasia, 3.9% and 5.1%, respectively. The malignant transformation occurred over 10 years. Conclusions: Patients with dysplastic leukoplakia have an increased risk of malignant transformation, but the risk is higher with laryngeal than with oral leukoplakia. There is no significant difference between the groups regarding survival with leukoplakia-associated cancer. Oral patients with no dysplastic lesions have a low risk of malignant transformation. A complete excision and long-term follow up are suggested for high-risk patients to diagnose cancer in an early stage and to control late (over 10 years) malignant events.

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