According to statistics gathered from the American Cancer Society (ACS), cancer death rates fell 32% from their peak in the 28-year period from 1991 to 2019. According to the CDC's data in the past decade, age-adjusted cancer deaths per 100,000 people in the US decreased from 173.5 in 2009 to 155.8 in 2016, and then decreased at a faster rate to 146.2 in 2019 for a total decrease of 16% in 10 years.

The ACS attributes the reduction in cancer deaths to such factors as decreased smoking, improved chemotherapy and other treatments, and more success with early screening of some cancers such as breast, prostate and colon cancers.

For cancer death rates to continue (or accelerate) their decline to 50% below today's levels before 2051, it will likely require multiple research breakthroughs in treatment and prevention. For example, there are potentials for advanced immunotherapies such as allogenic CAR T-cell therapy, in which a patient's own immune cells are modified to fight cancer. While current versions have limitations, researchers are working on off-the-shelf versions that could become a lot less expensive for the medical system.

Other potential game changers are inorganic nanoparticle-enabled cancer therapy (see Metaculus question here), cancer vaccines, and precision medicine.