A range of methods to target specific types of cell in the body are presently under development: immune cells, nanoparticles, viruses, and bacteria can all be used to deliver payloads to specific cells, provided that a suitable sensor mechanism can be established for the target in question. One of the benefits of this approach is that almost all existing methods used to destroy cells can be adapted for this new world of precision therapies. Tiny amounts of proven chemotherapy compounds can be loaded into nanoparticles and remain effective in destroying the cancer cells they are delivered to, but the severe side effects of standard chemotherapy are almost entirely eliminated. Chemotherapy in its present incarnation is a very unpleasant exercise, and targeting is a great leap forward in the application of chemical attacks on cancer.
Radiation is also used as a cancer treatment. As for chemotherapy, the present state of the art in available treatments involves a range of techniques that aim to to hurt the cancer more than the rest of the patient. It's still a pretty unpleasant exercise - not something that anyone would choose to undergo unless it were the least worst available option. Like chemotherapy compounds, radioactive compounds can also be cut down to amounts as small as individual atoms and loaded up onto nanoparticles or other delivery systems. For example, last month researchers reported on the use of a type of bacteria that only infects cancer cells as a carrier for radioactive materials that destroy those infected cells.
Tiny amounts of highly radioactive compounds are like tiny amounts of poison - they don't cause much harm at all outside the target cells, and this is the key to building therapies that have minimal side-effects. Here is another recent example of targeted therapy development using radioactive materials, but with nanoparticles as the delivery agent this time:
Cancers of all types become most deadly when they metastasize and spread tumors throughout the body. Once cancer has reached this stage, it becomes very difficult for doctors to locate and treat the numerous tumors that can develop. Now, researchers at the University of Missouri have found a way to create radioactive nanoparticles that target lymphoma tumor cells wherever they may be in the body.
In an effort to find a way to locate and kill secondary tumors [researchers] have successfully created nanoparticles made of a radioactive form of the element lutetium. The MU scientists then covered the lutetium nanoparticles with gold shells and attached targeting agents. [Previous research] has already proven the effectiveness of similar targeting agents in mice and dogs suffering from tumors. In that research, the targeting agents were attached to single radioactive atoms that were introduced into the bodies of animals with cancer. The targeting agents were able to seek out the tumors existing within the animals, which were then revealed through radio-imaging of those animals.
In their current research, the MU scientists have shown the targeting agents can deliver the new radioactive lutetium nanoparticles to lymphoma tumor cells without attaching to and damaging healthy cells in the process. "This is an important step toward developing therapies for lymphoma and other advanced-stage cancers. The ability to deliver multiple radioactive atoms to individual cancer cells should greatly increase our ability to selectively kill these cells."
Twenty years from now cancer will be comparatively well controlled: the trend is towards highly effective therapies, thousands of researchers are involved in building them, and a lot of money is flowing into this work. Cancer doesn't worry me anywhere near as much as common causes of sudden death in the elderly such as heart failure and stroke. If, against the odds, you find yourself nailed by cancer in the 2030s - and I think that this is an unlikely outcome for anyone in a wealthier region of the world - then even the worst case scenarios still allow you plenty of time to wrap up matters and arrange your own cryopreservation. Heart failure and stroke arrive with no such warning, and the only way to reliably deal with all of the causes of functional degeneration in the heart and brain is to implement SENS rejuvenation biotechnologies. Despite tremendous progress in recent years the SENS program remains in a comparatively early stage of funding and support within the research community - it is tiny in comparison to the cancer research community, and funding is the greatest obstacle to faster progress.