High-Yield Updates in Skin Cancer Treatment: Niacinamide, Squamous Cell Risk, Mohs for Melanoma, Antibiotic Prophylaxis, and Neoadjuvant PD-1 Therapy

Conclusions

• Niacinamide still appears effective for reducing non-melanoma skin cancer risk, and the best benefit may come from starting it earlier rather than waiting until patients have accumulated multiple prior skin cancers.
• The apparent cardiovascular safety concern around niacinamide is not supported by a large dermatology-specific cohort, suggesting the earlier signal was likely confounded by underlying cardiac risk.
• Low-stage squamous cell carcinoma can still behave aggressively, so intermediate features such as moderate differentiation, small-caliber perineural invasion, subcutaneous fat invasion, and lymphovascular invasion should raise concern even when BWH stage is low.
• Lymphovascular invasion is a particularly strong adverse prognostic factor in cutaneous squamous cell carcinoma and should be treated as a high-risk feature regardless of stage.
• Mohs surgery is best favored for melanoma in situ and lentigo maligna/lentigo maligna melanoma on the head and neck or other tissue-sensitive sites because these tumors often have substantial subclinical spread and higher recurrence with standard excision.
• Mohs surgery appears to reduce local recurrence and may improve disease-specific survival in lentigo maligna and lentigo maligna melanoma compared with wide local excision.
• Routine prophylactic oral antibiotics for lower-leg skin surgery do not clearly reduce postoperative infection rates, so antibiotic stewardship and alternative preventive measures should be considered.
• Neoadjuvant PD-1 immunotherapy for locally advanced or high-risk squamous cell carcinoma can produce high pathologic response rates and encouraging survival outcomes, making it an increasingly important preoperative option for selected patients.