Rhabdomyosarcoma in Karachi 1998-2002
The epidemiological features of rhabdomyosarcoma (RMS), an uncommon malignancy composed of cells with histopathologic features of striated muscle, were studied in Pakistan. Incident RMS cases recorded at the Karachi Cancer Registry during 1998 to 2004 were reviewed and to ensure maximum completness of data, only those registered between 1998 and 2002 were considered for the present study. Two hundred and seventeen cases were reported to the Karachi Cancer Registry during this five-year period. One hundred and forty eight of the patients (60.4% males; 39.6% females) were residents of Karachi. The crude and standardized annual incidence rates/100,000 were 0.3 for males and 0.2 for females. The incidence was 0.5 in children below 15 years of age. The primary RMS sites in males were head and neck (28.1%), extremities (25.8%), genitourinary (GU) tract (17.9%), trunk (9.0%), orbit (7.9%), and retroperitoneum (3.4%). RMS occurred at other sites in 7.9% of the patients. Corresponding frequencies in females were head and neck (35.6%), extremities (16.9%), GU tract (16.9%), trunk (8.5%), orbit (8.5%) and other sites in 13.6%. Approximately 60% of the cases were childhood RMS and three fourths were below 21 years. The mean age of RMS cases all sites, males, was 18.5 years (95% CI 15.6; 21.4); for childhood RMS, 7.5 years (95% CI 6.0; 9.2); and for adult RMS 34.2 years (95% CI 28.3;40.2). In females, the corresponding figures were 18.2 (95% CI 13.7; 22.7); 6.6 (95% CI 5.0; 8.1) and 33.9 (95% CI 27.5; 40.5), respectively. One hundred cases were retraceable, and the mean survival time, RMS all sites and ages in both genders, was 1.5 years (95% CI 1.1; 1.9). The 5-year survival was 10%, and 3-year survival was 30% whereas 16.7% of the patients died within a year of diagnosis. The indicators of poor prognosis, a late presentation, rapid evolution, advanced disease, tumor burden (tumor size > 5.cms) and regional lymph node involvement, are characteristic of RMS in Karachi. Recent advances in RMS multimodality treatment protocols have improved RMS prognosis in patients with limited disease. Pakistan should focus on early diagnosis and prompt treatment of malignancies. This requires health education for the general population to create awareness and training of health professionals at all levels to promote early diagnosis. An RMS group is required , which would monitor the treatment, recurrence, patient education and provide psychosocial support. Cytogenetic studies are advised for a better understanding of biologic differences in RMS cases in this population.