Suppressive effect of vitamin K 2 (menatetrenone) against bone mineral density loss after radiotherapy in uterine cancer patients.

Purpose: This study aimed to investigate whether vitamin K ₂ (menatetrenone) suppresses bone mineral density (BMD) loss in the irradiated region after radiotherapy (RT) in uterine cancer patients.
Materials and Methods: Our study included 34 patients who underwent whole pelvic irradiation for uterine cancer between 2001 and 2010. The patients were categorized in two groups: (1) Vitamin K ₂ (45 mg/day) administration group (group A) with 18 cases and (2) non-administered group (group B) with 16 cases. The duration of vitamin K ₂ administration was 1 year or longer. BMD was measured before and immediately, 3 months, 6 months, 1 year, 1 year or more after RT.
Results: Regarding change rate in the BMD of L3-L4 which was outside the irradiated field, no significant changes were observed in BMD after radiation in either groups compared to BMD before radiotherapy. Regarding change rate in BMD of L5-S1 which was inside the irradiated field, BMD reduced significantly at 6 months after radiotherapy compared to BMD before the start of radiotherapy in Group B (P = 0.0234). However, no significant change was seen in group A. Grade 2 and 3 insufficiency fractures appeared in both groups, one in each. Regarding outside the irradiation field, one patient developed compression fracture in L2 in group B, none occurred in group A _. CONCLUSION: We suggest that vitamin K ₂ could suppress the decrease in BMD due to whole pelvic radiotherapy. Further studies are needed in the future to improve quality of life such as the prevention of insufficiency fractures.
Competing Interests: Declarations. Conflict of interest: The authors state that there are no conflicts of interest. Ethical approval: This study has been approved by Institutional Review Board of Hiroshima University (Clinical Trial Registration number: E-1836). Patient identifiers were removed, and this study was conducted in accordance with the Declaration of Helsinki. Informed consent: Informed consent was obtained from all individual participants included in the study.
(© 2025. The Author(s).)