Believe it or not, a component of chocolate may inhibit angiogenesis (blood vessel formation) in human ovarian cancer cells. Cancers use this blood vessel formation so they can spread (metastasize). So chocolate may help prevent metastasis … the problem is the sugar in sweetened chocolate may feed some tumors …
   
Oncol Rep. 2000 Nov-Dec;7(6):1285-91.

Researchers found that Vitamin E suppresses telomerase activity in ovarian cancer cells selectively. In other words, it did not suppress telomerase activity in normal ovarian cells. Thus, it shortens the lives of cancer cells without shortening the lives of normal cells.
   
Cancer Detect Prev. 2007;31(2):119-28. Epub 2007 Feb

A recent meta-analysis on the use of vitamin E in cancer prevention found that:
  
“Vitamin E … was associated with a statistically significant reduction in the incidence of prostate cancer. Vitamin E can be used in the prevention of prostate cancer in men who are at high risk…”
  
Ann Saudi Med. 2007 Nov-Dec;27(6):409-14.

This study found that cannabinoid receptor agonists (such as marijuana) seem to be potent agents to help inhibit prostate cancer.
   
According to the study “Our results suggest that treatment of androgen-responsive human prostate carcinoma LNCaP cells resulted in a decrease in intracellular and secreted levels of PSA, with concomitant inhibition of androgen receptor, cell growth, and induction of apoptosis. We conclude that cannabinoids should be considered as agents for the management of prostate cancer
  
This may end up being useful as a preventative measure for people who are at risk for prostate cancer, though our society has a way to go to get over the negative stigma that Marijuana has.
   
A word of caution. Keep in mind that there are studies showing that, while safe in general, there are some people who can have adverse psychological effects from Marijuana. If there is a personal or family history of psychosis (schizophrenia, etc.), then it is probably best to avoid marijuana use since there is some evidence it could trigger it if you are already “predisposed”. There is little to no evidence that moderate doses of marijuana can induce psychosis in individuals that are not predisposed. However, high doses seem to be able to do that…. more information below.
   
Cancer Research 65, 1635-1641, March 1, 2005
   
Drug Alcohol Rev. 2004 Dec;23(4):433-43. Cannabis use and psychotic disorders: an update.
Hall W, Degenhardt L, Teesson M.
   
Office of Public Policy and Ethics, Institute for Molecular Bioscience University of Queensland Australia. w.hall@imb.uq.edu.au
   
The following is an abstract of the above study looking at cannabis use and psychosis
   
This paper evaluates three hypotheses about the relationship between cannabis use and psychosis in the light of recent evidence from prospective epidemiological studies. These are that: (1) cannabis use causes a psychotic disorder that would not have occurred in the absence of cannabis use; (2) that cannabis use may precipitate schizophrenia or exacerbate its symptoms; and (3) that cannabis use may exacerbate the symptoms of psychosis. There is limited support for the first hypothesis. As a consequence of recent prospective studies, there is now stronger support for the second hypothesis. Four recent prospective studies in three countries have found relationships between the frequency with which cannabis had been used and the risk of receiving a diagnosis of schizophrenia or of reporting psychotic symptoms. These relationships are stronger in people with a history of psychotic symptoms and they have persisted after adjustment for potentially confounding variables. The absence of any change in the incidence of schizophrenia during the three decades in which cannabis use in Australia has increased makes it unlikely that cannabis use can produce psychoses that would not have occurred in its absence. It seems more likely that cannabis use can precipitate schizophrenia in vulnerable individuals. There is also reasonable evidence for the third hypothesis that cannabis use exacerbates psychosis.

PMID: 15763748 [PubMed - indexed for MEDLINE]

Marijuana has gained recent interest due to its antitumor potential. However, some studies have shown that it can reduce VEGF. VEGF is important for the growth of follicles.
   
One study states “In vitro and in vivo experiments show that at least two mechanisms may be involved in this cannabinoid action: the direct inhibition of vascular endothelial cell migration and survival as well as the decrease of the expression of proangiogenic factors (vascular endothelial growth factor and angiopoietin-2)…”
  
So if you are trying to get pregnant, or especially if you are over 35 or have poor ovarian quality, you really want to avoid Marijuana. On the flip side, if you have cancer, you really want to consider getting a prescription for medical marijuana.    
Blazquez C, Casanova ML, Planas A, et al. Inhibition of tumor angiogenesis by cannabinoids. FASEB J 2003;17:529–31

Ok, very cliche for an herbal blog, but this is science. Marijuana (aka pot) is an herb. It has been used by Chinese Herbalists thousands of years back. The oldest herbal medicine texts describe the properties of Marijuana. So now, we have a new study looking at the effects of marijuana on malignant brain tumors. According to the study:
   
“cannabinoids inhibit the growth of different types of tumor cells, including glioma cells, in laboratory animals. They do so by modulating key cell signaling pathways, mostly the endoplasmic reticulum stress response, thereby inducing antitumoral actions such as the apoptotic death of tumor cells and the inhibition of tumor angiogenesis. Of interest, cannabinoids seem to be selective antitumoral compounds, as they kill glioma cells, but not their non-transformed astroglial counterparts“.
  
So it kills cancerous cells and helps prevent metastasis, but it does not affect benign cells.
  
Mol Neurobiol. 2007 Aug;36(1):60-7. Epub 2007 Jun 28.Links

Substances in legumes and soybeans (soyasaponins) were shown to induce cell death (apoptosis) in an aggressive Cervical Cancer cell line (Hela).  

Xiao JX, et al. Toxicol In Vitro. 2007 Aug;21(5):820-6. Epub 2007 Feb 9. Morphological study on apoptosis Hela cells induced by soyasaponins.
 
Xiao JX, et al. Exp Toxicol Pathol. 2007 Sep;59(1):35-42. Epub 2007 Jun 20. Soyasaponins inhibit the proliferation of Hela cells by inducing apoptosis.

Researchers in this investigation found that low doses of an Alcohol extraction (
but NOT a water extraction) of American ginseng increased human breast cancer cell proliferation in a breast cancer cell line. High doses inhibited breast cancer cell growth in both the alcohol and water extracts. Therefore, American ginseng should be safe to use with breast cancer patients if you make a tea from it, or if you use the alcohol extract in high doses.
 

Integr Cancer Ther. 2006 Sep;5(3):236-43.

A recent study demonstrates that acupuncture improves hot flushes and night sweats in breast cancer patients. According to the study

 

“The women, who had all been experiencing chronic multiple flushes and sweats, found the acupuncture helpful and relaxing. Many reported reductions in hot flush frequency, as well as improvements in overall emotional and physical well being. The group setting for treatment was regarded as supportive and encouraging.”
 
Complement Ther Clin Pract. 2007 Nov;13(4):250-7. Epub 2007 Aug 6.

The herb, Ichnocarpus frutescens was found to have significant anti-tumor activity in-vivo. The results of the study showed a significant decrease in tumor volume, viable tumor cell count and a significant increase of life span in the treated group compared to the untreated one: the life span of treated animals increased by 73.95% with higher doses of the herb.
 
Exp Oncol. 2007 Jun;29(2):94-101. Antitumor activity of polyphenolic extract of Ichnocarpus frutescens. Kumarappan CT, Mandal SC.