Why do the medical oncological professionals continue to promote and protect the practice of chemotherapy?

There are a few different reasons why medical oncological professionals might continue to promote and protect the practice of chemotherapy. First, it's possible that they genuinely believe that it's the best option for many cancer patients. Second, they may be financially incentivized to continue prescribing chemotherapy drugs, since pharmaceutical companies often give doctors kickbacks for prescribing their products. And finally, it's possible that there is some level of cognitive bias at play, whereby these professionals are more likely to believe information that confirms their existing views (i.e., that chemotherapy is an effective treatment for cancer), rather than information that challenges them.