Metachronous second primary cancers after successful partial laryngectomy for invasive squamous cell carcinoma of the true vocal cord.

The current retrospective studies documented the incidence, sites of occurrence, risk factors, and outcome of metachronous second primary cancers (MSPCs) among an inception cohort of 410 patients with invasive squamous cell carcinoma of the true vocal cord successfully treated with partial laryngectomy at a single institution. The Kaplan-Meier actuarial life-table method was used to document the relationship between the incidence of MSPCs and survival data. Univariate analysis was performed for potential statistical relationships among the incidence of MSPCs, the site of occurrence, and different variables. The overall incidence of MSPCs was 23.9% (98/410). The 10-year actuarial survival estimate for MSPCs was 20.4%. The incidence curve of MSPCs was linear, resulting in a 2%/y rate of development for MSPCs. In univariate analysis, the only variable that demonstrated a statistical correlation with the incidence of MSPCs was smoking, with MSPCs being statistically more likely to occur in smokers than in nonsmokers (p = .04). The main sites of origin for MSPCs were the lung (25.5% of cases), other non-upper aerodigestive tract sites (32.7%), and the upper aerodigestive tract (41.8%). The 10-year actuarial estimates for MSPCs were 9.1% in the upper aerodigestive tract, 7.1% in sites other than the lung or upper aerodigestive tract, and 6.6% in the lung. The incidence curve for MSPCs was linear, whatever the site of origin, resulting in 1 %/y, 0.7%/y, and 0.6%/y rates of development for MSPCs in the upper aerodigestive tract, sites other than the lung or upper aerodigestive tract, and the lung, respectively. Survival was statistically reduced when an MSPC developed; the 10-year actuarial survival estimates were 76.8% in patients who did not develop an MSPC and 43.7% in patients who developed an MSPC (p < .0001). Overall, 68.4% of patients who developed an MSPC (67/98) died of this disease. The 10-year actuarial survival estimates were 24% for lung MSPCs, 43.7% for non-lung, non-upper aerodigestive tract MSPCs, and 63.4% for upper aerodigestive tract MSPCs.