Chemotherapy used to treat a patient’s cancer increases that patient’s chances of developing cancer later in life in tissue adjacent to the original cancer, new research by the Buck Institute for Age Research indicates which appears in Tuesday’s online version of PLoS Biology.
In response to DNA damage (as it occurs during chemotherapy) cells either age or self-destruct (apoptosis, programmed cell death) if the damage cannot be repaired. It is a self protective response against unrepairable DNA damage in which cells shut down and stop dividing. The phenomenon where normal differentiated cells lose the ability to divide is called Cellular senescence. But this new study found out that when the cells shut down when DNA damage cannot be repaired, they start spewing proteins into their surrounding environment that cause inflammation and sets up conditions that support the development of age-related diseases including, ironically, cancer.
The study has major implications for age and cancer research because it suggests that the cellular response that protects us from DNA damage (as it occurs during chemotherapy) can promote disease at the same time in the long run.
Cells with damaged DNA are at risk of becoming cancerous tumors. These DNA-damaged cells become senescent to prevent any divisions. Although cellular senescence can suppress tumor formation from damaged cells by blocking the cell division that underlies cancer growth, it has also been implicated in promoting cancer and other age-related diseases. To understand how this might happen, the study measured proteins that senescent human cells secrete into their local environment and found many factors associated with inflammation and cancer development.
Different types of cells secrete a common set of proteins when they senesce. This senescence-associated secretory phenotype occurs not only in cultured cells, but also in vivo in response to DNA-damaging chemotherapy. Normal cells that acquire a highly active mutant version of the RAS protein, which is known to contribute to tumor growth, undergo cellular senescence, and develop a very intense senescence-associated secretory phenotype, with higher levels of proteins secreted. Senescent cells promote the growth and aggressiveness of nearby precancerous or cancer cells, and cells with a more intense senescence-associated secretory phenotype do so more efficiently.
The study, which compared tissue samples from prostate cancer patients before and after chemotherapy, provides a cautionary note for younger patients who receive treatments that could promote the development of further cancers later in life.
“Chemotherapy is brutal – both normal and cancerous cells are forced into senescence, with resulting secretion of inflammatory factors that can produce flu-like symptoms during treatment,” Judith Campisi, a member of the study, said. She also said that the findings in the study help explain why cancer patients feel so sick when they get chemotherapy.
Current DNA-damaging chemotherapy focuses on cells that divide rapidly – affecting cancer cells as well as all dividing cells including cells in the alimentary canal and hair follicles. Chemotherapy is not only pro-aging, but also pro-cancer, due to the fact that it produces more senescent cells that the body can eliminate which create proteins that cause inflammation and cancer.
Recommended Reading:
- Buck study: Chemotherapy may promote development of cancer later in life
- Senescence-Associated Secretory Phenotypes Reveal Cell-Nonautonomous Functions of Oncogenic RAS and the p53 Tumor Suppressor
- One in Five Cancer Clinical Trials Is Published
- Cancer data: Burying bad news
- Another Reason to Stand Up to Chemotherapy: Censured Data
- Chemotherapy: Why You Should Resist It
May 14, 2009 at 1:19 am
Treating cancer either with Conventional medicines, surgery or with Alternative Medicines is left up to the patient who suffers the disease. The patient must be confident enough to take up a treatment. I suggest Alternative Cancer Treatment as the best way to cure Cancer.