The research is ongoing, but signs are promising.
Cancer cells work by proliferating the growth of cells until tumors grow. These cells then invade healthy tissues, which leads to the various types of cancer.
There is a belief that the cells are able to “sense” each other, which allows them to come together to form the tumor. This “sensing” occurs via mechanical forces, meaning a lack of gravity could determine whether the cells can effectively communicate each other.
This is the basis behind ongoing experiments. Already, cancer cells placed in a microgravity environment (centrifuge) have been found to be unable to coagulate and therefore no tumors were able to grow. This was without drugs.
The next step is to send the experiment to space. No humans with cancer would go, it would simply be the cells. Scientists on the ground would monitor the growth of the cells.
The hope is to use microgravity in conjunction with modern drugs to produce better cancer-fighting treatments.
First story idea that comes to mind is a small-town resident, older, with an entire family, who somehow wins a trip to the International Space Station for treatment. Her cure could launch her into fame and the story could tell how fame, fortune, and an extended life aren’t exactly the future that would lead to the most fulfillment, with the recipient of the treatment dying alone after losing their relationship with family. With a juxtaposition of their life before and life after the cure this could be a cautionary tale for lottery winners.
Or, it could be a Charlie and the Chocolate Factory situation, where the ISS has all sorts of unique rooms and experiences which show the purity of spirit and at the end it’s deemed the person will be given a new, experimental cure.