https://www.metaculus.com/notebooks/8701/the-path-to-controlling-cancer/

Treating cancer is a battle against exponential growth of mutating cells, so even breakthrough drugs may offer only incremental increases in survival time before residual tumors rebound. But as we learn more about the fundamental mechanisms of cancer, we can target those processes more directly. When will people diagnosed with the most lethal cancers more often than not survive for years? I will examine progress in cancer treatment and speculate on the path toward managing intractable cancer types.

Why are several-year survival rates the currency of progress in fighting cancer? It is easy to wonder, especially if you have a personal connection to cancer, why we keep seeing breakthroughs that result in a small bump in survival times rather than cures. In short, cancer cells are human cells and they evolve. It is easy to kill cancer cells, but difficult to kill them without destroying the patient’s body. And it is extremely difficult to kill every one of them before they evolve again.

Most mutations either have no effect or they kill the cell and therefore self-correct. Even when mutations self-perpetuate against all odds, the body has many defenses against them. The chances of a combination of mutations evading all this is vanishingly small, but there are trillions of opportunities for it to happen in the body. By the time it is diagnosed, a tumor has already bested a solid wall of defenses.

That means there is no easy fix for cancer, and a variety of treatments are used—primarily different types of surgery, radiotherapy, and chemotherapy. The relative importance of each of these will continue to evolve.