Just in case you're not being facetious...Cancer is a label that groups a huge variety of diseases that involve "unregulated cell growth" (thanks Wikipedia!). Curing "cancer" is extremely difficult because it isn't one thing.
Then at least the cure for one type of cancer. I am okay with there being different cures for different types. What I am not okay with is that is that I haven't seen a cure for any type of cancer that doesn't boil down to lets kill a ton of cells using methods that are slightly less likely to kill normal cells than cancer cells.
Let me introduce you to one type of cancer: chronic myelogenous leukemia. A friend of mine has it. Previously, the prognosis was terrible. Since the development of imatinib, survival rates are basically like anybody else.
Many types of cancer that were uniformly fatal 50 years ago now have near-100% survival rates. The easier ones have been cracked. The hard ones are left.
The reason cancer is so hard to fight is that it's not so much a single type of bad cell but an evolutionary process (see: clonal evolution) that continues to generate hardier bad cells. Cancer is when cells become individually fit (in an aggressive way) at the expense of the organism. Cancer isn't one undesirable mutation; a typical cancer cell has at least 5 detectable mutations. It's a process.
The perversity is that cancer treatments are themselves carcinogenic (of different cancers) because the stress on the body (exposure to cellular toxics) causes faster mutation and creates more opportunities for mutant cells (that thrive amid the toxin, at least differentially) to take over.
This is also why cancer can stop responding to treatment. It's like antibiotic resistance.
People are working on more targeted treatments (including minimally invasive ones like radiofrequency ablation) than the typical systemic chemotherapy. The problem is that these are best used with early detection. At Stage IV, the cancer is likely to be all over the body and systemic treatments are necessary... but there are limits to how far those work.
I want to thank you for that answer, it is the first explenation I have been given that doesn't simply point out that doctors and their relatives also die of cancer (but what single doctor can found even a single research cure? FDA approval would take years and not be very certain at all).
But you say that some of the easier cancers have already been cured (near 100% survival rate, which is as good as it gets since it would always be possible to discover too late), or mostly so: do you know why this haven't been more widely published or talked about? I mean we haven't cured all infectiones diseases (or even the common cold), but when the cure was found for polio it was massively published, to the extends that court rooms took a break to hear the announcements.
There are only a few cancers which can be cured eventhough they have spread everywhere. One of these are testicular germ cell tumours (eg Lance Armstrong), as well as some rare types of gestational trophoblastic disease (essentially out of control placenta) and acute leukaemia and lymphoma. It's not big news because these tumours are quite rare, and treatment for leukaemia/lymphoma has always worked better than for solid tumours. There is also nothing to be gained from a public health persepctive by telling people that testicular cancer can be cured with multiple cycles of chemo, surgery and radiotherapy.
Some cases of advanced colon cancer can be cured if the disease has only spread to the liver, by cutting out the disease in the liver.
But your most common cancers eg breast, lung, colon for the most part, gastric,prostate... they aren't curable once widespread.
Because not all people get all cancers. There are a lot of different types of cancer. If you get really really lucky, you get a benign tumor which can just be cut out and is pretty much gone forever.
That's a very good explanation. I would add that a 'cancer' takes 15 - 20 years to develop from one original cellular derangement to a clinically obvious tumour. we arrive in the last 12 months of the process and try to affect cure on this diverse, evolved cellular civilisation. No wonder we fail.
Harnessing the immune system however - now that could be more promising as an approach that the cancer can't evolve away from as easily eg announced just last week: http://www.ascopost.com/ViewNews.aspx?nid=4189
I wouldn't just say cancer is about "unregulated cell growth". What it's about is a conflict of interest at the cellular level. Some cells become individually fit at the expense of the highly specialized civilization called an organism. It's not just "growth" (mass effect) that makes them so dangerous, because if it were only that, the cancer would just displace stuff (like a benign tumor which, contrary to the name, can kill you-- especially in the brain, where displacement can be fatal because location/connection matters). In addition to reproduction, cancers steal resources from (and starve) or invade healthy cells and cause organs to fail.
The underlying theme isn't just "cell growth". It's about cells that override the body's mechanisms for coupling individual fitness with the body's needs. Much of what makes the disease hard to treat is that cancer cells become increasingly fit (individually speaking) over time, and while systemically damaging the environment (e.g. chemotherapy, radiation) works great if it kills all of them, if it doesn't, it leaves an even more fit subset alive.
