Second primary tumors in laryngeal cancer: results of long-term follow-up

Abstract

Purpose: The development of second primary tumors (SPTs) is the most important factor determining the survival in early-stage head and neck cancer patients, whose first tumor has been successfully treated. New methods of examining genetic changes have raised doubts about the validity of the widely held field cancerization hypothesis as the cause of SPTs, and an alternative hypothesis of monoclonal origin has been proposed. The objectives of this study were to look at the pattern of development of SPTs and the possible factors influencing the incidence of SPTs and the survival in early-stage laryngeal cancer with long-term follow-up. Methods and Materials: One hundred forty-four consecutive patients of T1N0M0 squamous cell carcinoma of the true vocal cord treated with definitive radiotherapy between 1976 and 1992 were analyzed. The incidence, time to development, and survival of aerodigestive and other SPTs were noted. p53 overexpression indicating a mutated p53 gene was analyzed by immunohistochemistry. Results: With a median follow-up of 6 years (range 2–20 years), 42 patients developed a SPT, 24 in upper aerodigestive tract and lung and 18 at other sites. The actuarial incidence of developing a SPT at 5, 10, and 15 years was 23%, 44%, and 48.7% respectively. The median time interval for development of SPT in an upper aerodigestive tract was 21 months as opposed to 50 months for other sites ( p = 0.02). The most common sites of SPTs included lung for upper aerodigestive tract; and prostate, followed by colon, for other sites. The actuarial risk of developing a nonaerodigestive SPT at 5 and 10 years was 35% and 55% respectively. p53 status affected neither the incidence of SPT nor the survival. SPTs were the leading cause of death in these early-stage laryngeal cancer patients. Conclusion: The origin of SPTs seems to be multifactorial, involving both the field cancerization effect and an increased baseline genetic predisposition. Until more reliable genetic markers are developed, chemoprevention remains the best treatment option at preventing SPTs in these early-stage patients.