Identifying men at greatest risk of weight gain from androgen deprivation therapy.

80 Background: Androgen deprivation therapy (ADT) is a mainstay of prostate cancer therapy. Weight gain is among the adverse metabolic changes associated with ADT, and may contribute to cardiovascular comorbidity. A better understanding of the risk factors for weight gain on ADT is important for optimal management of ADT-associated morbidity. Methods: A retrospective review assessed weight change among 118 men with nonmetastatic prostate cancer treated with ADT. The primary endpoint was weight change at one year from ADT initiation, with the secondary aim to stratify risk of weight gain by baseline patient characteristics. Statistical analyses were performed using two-tailed t-tests and linear regression. Results: Men in our cohort exhibited a significant increase in weight (p=0.0005) in the one year following ADT initiation. Three risk factors for weight gain on ADT were identified: younger than age 65 (5.98 pounds gained, p=0.001 vs. 1.63 pounds, p= 0.09 for age 65+), body mass index (BMI) less than 30 (4.36 pounds gained, p=0.00002 vs. 0.22 pounds, p=0.87 for BMI 30+), and non-diabetic status (3.43 pounds gained, p=0.0003 vs. 0.57 pounds, p=0.74 for diabetics). An aggregate risk scoring system was contrived to allow for weight change prediction by total number of risk factors present: scores of 0, 1, 2, and 3 risk factors corresponded to weight changes of -2.42 (p=0.43), +0.9 (p=0.56), +2.9 (p=0.01) and +8.3 pounds (p= 0.0001) respectively. Weight gain increased significantly with increasing risk score (p-trend= 0.0005), decreasing baseline age (p-trend= 0.004) and decreasing baseline BMI (p-trend= 0.01). Conclusions: Younger than age 65, BMI less than 30, and non-diabetic status were each significantly associated with weight gain one year after starting ADT. Increasing weight gain was strongly associated with increasing number of baseline risk factors. Although metabolic consequences were previously considered most significant for patients with preexisting comorbidity, these data suggest younger, slimmer, and non-diabetic patients may be at higher risk for gaining weight on ADT. As these three categories of men generally have higher endogenous testosterone (T) levels prior to ADT compared to older, obese, and diabetic men, the magnitude of T decline following ADT might explain these findings.