Cancer recurrences and second primary cancers after use of antihistamines or antidepressants

Objective: Reports in the scientific literature have described accelerated tumor growth in association with antidepressant and antihistamine exposure in experimental rodent cancer models. This study was designed to determine whether exposure to prescription antidepressants or antihistamines is associated with tumor growth in humans. Methods: Two nested case-control studies were conducted with a cohort of 1467 patients with breast cancer, colon cancer, or melanoma diagnosed between 1988 and 1994. Eligible patients includes 95 with a cancer recurrence and 78 with a second primary lesion diagnosed during the follow-up period. Five control subjects were matched to each case patient according to cancer site, stage, and follow-up time. Conditional logistic regression was used to compare risk for tumor recurrence or occurrence of a second primary tumor among patients using antidepressants or antihistamines with risk among unexposed patients. Results: For a cohort of patients who were predominantly female (78%), with breast cancer (57%) and with a tumor in situ or with localized disease (79%), the average age was 62 years at cancer diagnosis and average duration of follow-up period was 2.2 years. Use of antidepressants or antihistamines was unrelated to risk for tumor recurrence (odds ratio, 0.97; 95% confidence interval, 0.52 to 1.78) or second primary tumors (odds ratio, 0.94; 95% confidence interval, 0.50 to 1.77). Conclusion: Typical use of antidepressant or antihistamine drugs did not increase risk for recurrent or second primary tumors among patients with cancer.