Quite good and thorough answer. This only works for mixing liquids with the same (or close enough) chemical compositions though. With two different liquids reactions might take place though, altering the final amount of heat dramatically. The enthaply of mixing might be positive or negative as well. Therefore, mixing two different solutions at the same temperature can consume or produce heat as well.

No, I don't agree. How do you define "help"? A localized treatment can never heal a systemic disease, like metastatic cancer. I detailed exactly under which circumstances it could be a beneficial treatment.

That's not true. Even if the tumor has metastazised, it is still very possible that the primary tumor ultimately provokes fatal consequences. To take the example of my mother, her pancreatic tumor grew to block the veins draining the kidneys. While her ultimate cause of death was pancreatic cancer, the proximate was kidney failure, exacerbated by severe dehydration from ileus which resulted from the peritoneal metastases of the pancreatic cancer. Her kidney function before the ileus developed was at only 15 %, which is a kidney failure by definition.

Even before metastases develop, a large proportion of tumors is inoperable due to involvement of blood vessels. This group of patients is the target for these treatments. In pancreatic cancer the tumor microevironment, mainly the pancreatic stellate cells hinder the effectiveness of chemotherapy. Radiotherapy is limited in its applicability by the sensitivity of surrounding tissue, namely the small intestine. It is therefore great to have different treatment options. Future studies will show the effectiveness in comparison with established treatment regimes and this may or may not be an improvement.