Presentation, prognostic factors and patterns of failure in adult rhabdomyosarcoma

The purpose of our study is to retrospectively review our institutional experience with adult rhabdomyosarcoma (RMS) to determine presentation, prognostic factors and patterns of failure in this disease.

All patients >/= 16 years with a diagnosis of rhabdomyosarcoma were retrospectively reviewed. Tumors were classified according to the Intergroup Rhabdomyosarcoma Study (IRS) staging and grouping system. Median follow-up for surviving patients was 12.5 years.

A total of 39 patients (23 male, 16 female) were seen at our institution from 1961 to 1999. Median age was 45 years, and age distribution showed a bimodal peak at the late teens to twenties and later in the sixties. Tumor in the extremity was most common as seen in 15 (39%); this was followed by head and neck in 11 (28%), genitourinary in eight (20%), trunk/retroperitoneum in four (10%) and other in one (3%). Tumor stage was T1 in 21 (52%) while 26 (67%) were > 5 cm in size. Pleomorphic histology was most common (36%) and increased in incidence according to age category: 0% for ages 16-19, 27% for ages 20-49 and 60% for ages >/= 50 years old (P < 0.01). The median survival for the entire population was 2.25 years with a 5-year overall survival rate of 35%. Multivariate analysis identified early IRS stage (P < 0.001), non-embryonal histology (P < 0.009), favorable site (P = 0.024), female gender (P = 0.034), early T-stage (P = 0.034) and absence of nodal metastases (P = 0.037) as predictors of a better survival. The 5-year progression-free survival rate was 21%. Female gender (P = 0.002), non-embryonal histology (P = 0.009), early IRS stage (P = 0.02) and early T stage (P = 0.033) were found on multivariate analysis to predict for improved progression-free survival. The 5-year local control rate was 51%, and multivariate analysis found that only early T-stage was predictive of better local control (P = 0.045). Five of six Group II patients and five of eight Group III patients who received radiotherapy (RT) were locally controlled. Only one of five Group III patients was locally controlled without RT.

The overall prognosis of adult RMS is worse than reported in children, but age criteria within the adult population did not further classify outcome. RT is an effective local modality providing local control in almost all Group II and majority of Group III patients.