I am a medical aid for a cancer patient at this moment in time and as a coincidence he has also heavily abused cocaine and heroin upon learning of his diagnosis. I don't blame him, but I'll try to shed some light on how cancer maintains itself even in harsh environments. EDIT: His cancer is Stage III Non-Hodgkin's Lymphoma originally started in the larynx, but has progressed to the intestines, brain, spine, and the lymphatic nodules in relation to the neck.
First off the cancer itself undergoes a vast rearrangement and alterations to its metabolic mechanisms during the initial oncogenesis phase and subsequently leading into the initial tumor growth. Bolinas is correct in that cancer prefers glucose as a fuel, but it does not harness the glucose for its own energy production and rather allocates the resource for other secondary anabolic reactions. This is referred to as the "Warburg Effect". I have an article that I could send you that could go into extensive detail about its various activities. A lot of people are still stuck on the misconception that the cancer doesn't have a properly functioning mitochondria to produce ATP, but that is an old theory proven incorrect and yet it still somehow survives. It heavily exploits the cells mitochondrial center which also explains why many have had success utilizing mitochondrial inhibitors to destroy these cells either in vitro or in vivo.
Its ability to exploit the mitochondria also explains why cancer cells can feed upon the lactate through an metabolic process referred to as the Cori Cycle.
Quick guide illustrating the mode of action from which cancer produces various energy resources...
https://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/gluconeo.htm
The usage of lactase and the metabolic process that occur in conjunction with the tumor's stoma is also why cancer is referred to as being highly glutamine dependant. Glutamine within the tumor can be used for either oxidative metabolism or for a reductive metabolism such as lipid biosynthesis. Now the rapid lipid synthesis that is recognized in cancer is not completely understood, but it may be a mode of harvesting biological membranes that allow for further proliferation through the body. Hence the term "malignant". So if you were to examine a cancer's fuel source and remove certain variables that allow it to continue with its cellular proliferation it seems that it can and will adjust its metabolic procedures in correlation with what environmental factors are occuring. I'm in no way, shape, or form an oncologist. I just happen to be a medical aid for an individual who has cancer and thus gives me the desire to do research on my own.
Here is an informative article in regards to the "Warburg Effect" and its reversal counterpart.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3236330/ Sorry if it seems like a ramble. It probably was. The articles are a gold mine.
To answer the question I feel it would be hard to accurately say that cocaine can become an attributing factor to the increase in cancerous cell proliferation throughout the body. I'm sure creating a more stressful environment due to poor nutrition and sleep obviously doesn't help a cancer patient, but there is more compounding factors that are more pertinent in its survival than excessive dopamine/seratonin release.
