Excess of early onset multiple myeloma in endometrial cancer probands and their relatives suggests common susceptibility.

OBJECTIVE: Determine whether there is an association between uterine cancer and multiple myeloma.
METHODS: Data on second malignancies were obtained for 368 uterine corpus cancer patients treated between 1992 and 2005. Detailed family histories were devised for 192 probands. Diagnoses of multiple myelomas, lymphomas and leukemias in family members were medical record verified. The frequency of multiple myeloma among uterine cancer patients was compared to the female age-adjusted incidence rate of multiple myeloma obtained from the SEER database. The crude rate of multiple myeloma (as well as Hodgkin's, non-Hodgkin's lymphomas and leukemias) among first-degree relatives of patients with uterine cancer was compared to the age-adjusted incidence rate of multiple myeloma in the general population. Descriptive statistics were used to evaluate disease and cohort characteristics. A P value less than 0.05 was considered statistically significant.
RESULTS: Two of 368 uterine cancer patients were also diagnosed with multiple myeloma, both at age 50. The observed incidence of multiple myeloma in this cohort (543 per 100,000; 95% CI: 66-1962 per 100,000) represents a 120-fold increase based on predicted incidence (P=0.00014). The frequency of multiple myeloma in first-degree relatives was 2/1351 (148 per 100,000; 95% CI: 14.8-533 per 100,000) which represents a 27-fold increase compared to the general population (P=0.0026). The frequencies of leukemias and lymphomas in these family members on the other hand were not significantly increased (P=0.152 and P=0.218).
CONCLUSION: This specific excess frequency of early onset multiple myeloma in endometrial cancer probands and their relatives suggests shared susceptibility.