AN INCREASED RELATIVE FREQUENCY OF RETINOBLASTOMA AT A RURAL REGIONALREFERRAL HOSPITAL IN MIRAJ, MAHARASHTRA, INDIA

Background. Retinoblastoma is a relatively uncommon childhood malignan t neoplasm, It has been suggested previously that there is an increase d incidence of retinoblastoma in India, but this has been reported pri marily from urban cancer centers and may have been confounded by a ref erral bias. Methods. The authors have evaluated the relative frequency of tumors in children younger than 15 years of age from 1987 to 1990 at Wanless Hospital, a rural regional referral hospital in India. Resu lts. Of 158 children with malignant neoplasms, 13% (20) had the histol ogically confirmed diagnosis of retinoblastoma. Assuming that these 15 8 children represent a nonbiased reflection of childhood cancer incide nce in this region, these 20 cases of retinoblastoma represent a 3.3-f old increase over the expected number estimated with worldwide relativ e frequencies and a 4.4-fold increase over the relative frequency expe cted among a similar group of children as estimated with United States rates. The proportion of children with bilateral disease was 15%, whi ch is less than expected (20-30%). The mean age at presentation was 41 +/- 14 months (mean +/- standard deviation) compared with 26 months i n Western centers. In addition, 50% had metastases at the time of diag nosis compared with 5-10% at Western centers. The increased rate of me tastases and late age at diagnosis suggest of a diagnostic delay. Conc lusions. These results, in combination with previously reported increa sed relative frequencies from urban cancer centers in India, suggest t hat there may be a true increase in the incidence of retinoblastoma in India. The increase in unilateral retinoblastoma indicates that envir onmental factors may contribute to an increase of the nonheritable for m in India.