I previously posted some information on why patients with MS would have an increased risk of developing certain types of cancer, such as breast cancer and lymphoma, on this thread. general-discussion-f1/topic22806.html
One reason would be due to the elevated levels of homocysteine found in patients with MS (studies posted on above mentioned thread). Homocysteine is linked to breast cancer because it directly damages DNA and also because it interferes with nitric oxide, which regulates vascular endothelial growth factor. In the following study the researchers stated that plasma homocysteine (Hcy) is a well known independent risk factor for coronary heart disease, and is also a risk factor for cancer. In addition, the researchers found that homocysteine increased in parallel with the growth of tumor cells. The study concluded, “Conceivably, Hcy may be used as a more accurate tumor marker for monitoring cancer patients during treatment, and hyperhomocysteinemia as a risk factor for carcinogenesis.”
Hyperhomocysteinemia is a risk factor for cancer and a new potential tumor marker.
Wu, L.L., J.T. Wu. 2002. Clin Chim Acta 322(1-2):21-8.
“Plasma homocysteine (Hcy), a well-known independent risk factor for coronary heart disease, is also a risk factor for cancer. Results from our studies indicate that Hcy could be used as a tumor marker. We found elevated circulating total homocysteine (tHcy) in cancer patients even though they were not treated with anti-folate drugs. In serial specimens from cancer patients undergoing treatment, the change of tHcy coincided with the concentration of tumor markers. The rapid proliferation of tumor cells contributed to the much higher concentrations of circulating tHcy. Both concentrations of tHcy and tumor marker would increase in parallel during the growth of tumor cell, but only the Hcy concentration would decline in response to tumor cell death…Conceivably, tHcy may be used as a more accurate tumor marker for monitoring cancer patients during treatment, and hyperhomocysteinemia as a risk factor for carcinogenesis."
There would be numerous other reasons as well. For instance, the elevated levels of "prolactin" found in MS patients (studies posted on above mentioned thread). Research has shown that more than 95 percent of breast cancers express the receptor for prolactin (Reynolds, 1997). In the following study the researchers stated
that prolactin can promote cell proliferation and survival, increase cell motility, and support tumor vascularization. In addition, the researchers stated that a recent study of 235 cases reported a “significant positive association” between prolactin levels and breast cancer risk.
Prolactin and breast cancer risk.
Tworoger, S.S., S.E. Hankinson. 2006. Cancer Lett. 243(2):160-9. Epub 2006 Mar 10.
“Prolactin, a hormone involved in normal breast development and lactation, has been hypothesized to be important in the etiology of breast cancer… Experimental evidence indicates that prolactin can promote cell proliferation and survival, increase cell motility, and support tumor vascularization. Animal data suggest that prolactin can increase tumor growth rates and the number of metastases, as well as induce both estrogen receptor +(ER) and ER--tumors in a transgenic mouse model in which ER+ tumors are very rare. Epidemiologic data for premenopausal women are sparse; however a recent study with 235 cases reported a significant positive association between plasma prolactin levels and breast cancer risk. Studies in postmenopausal women have reported a positive association as well, and in the largest study (n=851 cases) the association was strongest for ER+ tumors. Overall, the available data support the hypothesis that prolactin increases risk of breast cancer…"