Why does chemo cure some cancers and not others? A good question and one that we still can’t answer fully. I read a recent technical article about why some cancers are cured with chemotherapy and others aren’t in the Journal “Nature Clinical Practice – Oncology“. It was freely available in a sample issue in January 2009 (although it might not be free for long, so if you are interested I would follow the link now) It is called “Why does cytotoxic chemotherapy cure only some cancers?” by Philip Savage (and others) January 2009 Vol 6 No.1 Nature Clinical Practice.
The article was written by four medical oncologists from London, UK. The point out that some tumours (often quite rare ones) can be completely cured with chemotherapy, however most of the common ones can not. Which tumours can be cured and why is this?
Chemotherapy Curable Cancers (even if they have spread)
- 1 Testicular cancer
- 2 Ovarian germ cell tumours
- 3 High grade non Hodgkin’s lymphoma (B cell and T cell)
- 4 Gestational choriocarcinoma
- 5 Hodgkin Lymphoma
The article says that most chemotherapy drugs act as cell poisons (e.g. by damaging DNA, or damaging the cells internal skeleton), what is important is what happens after the cell has been poisoned, i.e. does the poisoned cell die or not.
Obviously you want a poisioned cancer cell to die quickly and easily so it doesn’t spread. The point of this article is that the types of cancer that can be cured with chemotherapy (even when they have spread) tend to die easily.
Cells (both normal and cancer) often die by “apoptosis” and most cells need a working protein called p53 to die. The chemotherapy curable cells tend to have normal p53 DNA and it works as it should. The cells that are harder to cure by chemotherapy tend to be hard to kill (i.e. “resistant to apoptosis”), they often have a damaged p53 or it doesn’t work as it should.
So what does this all mean? Well basically some types of cancer are curable because they started from cells that are designed to die. If a cancer develops in a cell that is meant to live a long time and be resistant to death (e.g. a nerve cell) then it is harder to cure this type of cancer with chemotherapy.