I think fasting is her best chance. If you do a search on this forum, there was discussion of the Russians experimenting with dry fasting for cancer cures. Others on this forum have experienced healing of cancer with fasting.
From what I understand of cancer, it feeds off of glucose. When fasting, your body no longer uses glucose for energy but converts fat to ketones. The glucose is no longer available for food for the cancer. The cancer will "starve".
Ketones also can combine with foreign objects, such as toxins or cancer, in the body and as they are expelled, the foreign object they have attached themselves to are expelled as well.
The problem is that your mum will probably think fasting is crazy or stupid and that the doctors who are eager to take her money are gods. Therefore your mum will rather line the pockets of the crooks rather than let nature do what it was designed to do.
More importantly, disease is often given by God for a reason. Perhaps you mom is not right with the Lord, or there are people in her life that need to have their priorities refocused. I hope she can take some time reading the Bible in these difficult times. If she does, she will see that there are dozens and dozens of examples of people in peril that turn to fasting and prayer and see their burdens lifted and their prayers answered. Fasting in the Bible was done as a means of showing God that one was humbled before Him and that they were sincere about their petitions. Fasting in the Bible was done for spiritual reasons, and the physical benefits were just a pleasant side effect.
Sadly today, many would rather suffer sickness and even death than temporarily give up the pleasures of food. I hope your mom is different.