One of the effects of chemotherapy is a reduction in testosterone level in both sexes. The loss happens with aging, even without cancer and cancer treatment.
So the need for vitamin D is all the greater for those who have been through treatment, because we have even lower testosterone levels than those who never had cancer and chemotherapy.
Testosterone supplementation may be important for more than just beneficial effects on libido, but my point is primarily just to explain why it is that our need for additional vitamin D is so important.
http://www.pubmedcentral.nih.gov/art...?artid=2680613
AlaskaAngel
P.S. I do use a low-dose testosterone supplement .