Below is series of medical research studies links from the National Institute of Health. The focus is on the impact of Cannabis & Cancer.  Most of these studies were done outside of United Stated due to the restrictive nature of NIDA and the DEA doing any studies that show a positive impact of cannabis for medical use.  At the end, there is a list of articles compiled by the International Association of Cannabis Medicine..

Studies on Cannabis & Tumor cells:

Cannabidiol inhibits human glioma cell migration through a cannabinoid receptor-independent mechanism http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1576089 

The expression level of CB1 and CB2 receptors determines their efficacy at inducing apoptosis in astrocytomas http://www.ncbi.nlm.nih.gov/pubmed/20090845 

In vivo effects of cannabinoids on macromolecular biosynthesis in Lewis lung carcinomas http://www.ncbi.nlm.nih.gov/pubmed/616322 

Cannabinoid receptor systems: therapeutic targets for tumour intervention http://www.ncbi.nlm.nih.gov/pubmed/14640910 

Predominant CB2 receptor expression in endothelial cells of glioblastoma in humans http://www.ncbi.nlm.nih.gov/pubmed/19480992 

Hypothesis: cannabinoid therapy for the treatment of gliomas http://www.ncbi.nlm.nih.gov/pubmed/15275820 

Involvement of cannabinoids in cellular proliferation http://www.ncbi.nlm.nih.gov/pubmed/15638794 

Cannabinoids induce apoptosis of pancreatic tumor cells via endoplasmic reticulum stress-related genes http://www.ncbi.nlm.nih.gov/pubmed/16818650 

Cannabinoids and gliomas http://www.ncbi.nlm.nih.gov/pubmed/17952650 

Opposite changes in cannabinoid CB1 and CB2 receptor expression in human gliomas http://www.ncbi.nlm.nih.gov/pubmed/20307616 

The stress-regulated protein p8 mediates cannabinoid-induced apoptosis of tumor cells http://www.ncbi.nlm.nih.gov/pubmed/16616335 

The CB2 cannabinoid receptor signals apoptosis via ceramide-dependent activation of the mitochondrial intrinsic pathway http://www.ncbi.nlm.nih.gov/pubmed/16624285 

Anti-tumoral action of cannabinoids: involvement of sustained ceramide accumulation and extracellular signal-regulated kinase activation. http://www.ncbi.nlm.nih.gov/pubmed/10700234 

Down-regulation of tissue inhibitor of metalloproteinases-1 in gliomas: a new marker of cannabinoid antitumoral activity? http://www.ncbi.nlm.nih.gov/pubmed/17675107 

Antitumor effects of cannabidiol, a nonpsychoactive cannabinoid, on human glioma cell lines http://www.ncbi.nlm.nih.gov/pubmed/14617682 

Endocannabinoids as emerging suppressors of angiogenesis and tumor invasion http://www.ncbi.nlm.nih.gov/pubmed/17342320 

Cannabinoid receptors in human astroglial tumors http://www.ncbi.nlm.nih.gov/pubmed/16893424 

Cannabinoids induce cancer cell proliferation via tumor necrosis factor alpha-converting enzyme (TACE/ADAM17)-mediated transactivation of the epidermal growth factor receptor http://www.ncbi.nlm.nih.gov/pubmed/15026328 

Delta9-tetrahydrocannabinol inhibits cell cycle progression in human breast cancer cells through Cdc2 regulation http://www.ncbi.nlm.nih.gov/pubmed/16818634 

Pharmacokinetics and pharmacodynamics of cannabinoids http://www.ncbi.nlm.nih.gov/pubmed/12648025 

Cannabidiol inhibits angiogenesis by multiple mechanisms http://www.ncbi.nlm.nih.gov/pubmed/22624859 

Chemopreventive effect of the non-psychotropic phytocannabinoid cannabidiol on experimental colon cancer http://www.ncbi.nlm.nih.gov/pubmed/22231745 

The cannabinoid delta(9)-tetrahydrocannabinol inhibits RAS-MAPK and PI3K-AKT survival signalling and induces BAD-mediated apoptosis in colorectal cancer cells http://www.ncbi.nlm.nih.gov/pubmed/17583570 

Colon carcinogenesis is inhibited by the TRPM8 antagonist cannabigerol, a Cannabis-derived non-psychotropic cannabinoid http://www.ncbi.nlm.nih.gov/pubmed/25269802 

For more studies and reports see International Association of Cannabis Medicine list of studies with links.  Note: some of the IACM links have a typo so the PublMed link is also included.