Influence of a Child's Sex on Medulloblastoma Outcome

Reviewers: Kenneth Blank, MD and Leonard Farber, MD
Source: Journal of the American Medical Association, Vol 279, No. 18

Medulloblastoma is the most common brain tumor of childhood. Despite aggressive therapy with surgery, radiation and chemotherapy the 5-year overall survival rate is 50%. Radiation of medulloblastoma includes the entire brain and spinal cord. Chemotherapy often lasts a year or more. These treatments, as well as aggressive surgery to remove the entire tumor, hold considerable side effects including neuro-psychiatric deficits, short stature and hormonal imbalances later in life.

Attempts have been made to define prognostic factors for children afflicted with this disease, with the idea that low risk patients may have their tumors cured with less aggressive treatment strategies, thereby avoiding the debilitating side effects. To date, the two most consistent prognostic factors reported are age and total resection of the tumor. In fact, medulloblastoma patients are divided into two groups high risk and low risk. The latter group is defined as children over 3 or 4 years of age who have had their tumors entirely removed and have no evidence of tumor spread. A recent report appearing in the May 13th edition of the Journal of the American Medical Association looks at the affect of sex on outcome.

The authors undertook a retrospective review of 109 medulloblastoma patients, age 21 years and younger, all of whom were treated at the University of California, San Francisco with surgery, radiotherapy and often chemotherapy. Univariate analysis of prognostic variables found stage (low versus high risk), female sex, total tumor resection and lack of disease spread at presentation to significantly predict for increased survival. Dosing chemotherapy, treatment era (prior to 1979 versus 1979-1984 versus 1985-1989 and after 1990) did not affect outcome. In addition, radiotherapy dose did not affect outcome. A multivariate model predicting for survival using sex, age, metastasis at presentation, extent of surgical resection of the tumor found female sex, total resection and lack of disease spread at presentation predicted for increased survival.

Why females do better than males is perplexing. However, this is not uncommon in childhood tumors. As the authors write in this paper, "there is a clinical axiom in oncology that 'girls are good, boys are bad'. Girls may be more sensitive to treatment (chemotherapy and radiotherapy) and the onset of precocious puberty may play a role but this is entirely unproved. Large national clinical trials may use the information reported here to tailor treatment schemes for patients with different prognosis.