Chemotherapy is a therapy that uses chemical substances that have cellular toxicity, to affect sick cells in order to destroy them. Quite often several substances are combined to increase their effectiveness, especially if the cancerous disease spreads. The different drugs can be administered by intravenous injection (infusion) or orally (tablet). The molecules affect the diseased cells, but unfortunately also the healthy cells indiscriminately, which often causes more or less pronounced side effects, depending on the individual sensitivity of the person (loss of appetite, loss of hair, nausea, vomiting, severe fatigue).
Regarding breast cancer, since the screening was introduced, i.e. over the last thirty years, the percentage of patients undergoing chemotherapy has risen from 20% to around 80%. Chemotherapy for breast cancer also has effects on survival, comfort of life and other morbid effects for these treated patients.
Researchers warn on the over-detection of cancers that would never have impacted the lives of patients if they had not been discovered (over-diagnosis); the consequence is over-treatment, wherever screening is done, the number of mastectomies, radiotherapies (see relevant chapters) and chemotherapies have increased. All cancers that have been detected, real cancers as well as those that would not have progressed, are treated.
Scientists warn on the increased mortality due to over-treatment, and several studies suggest that the toxic effects of the treatments administered cancel out the hypothetical benefit of screening, which has already been widely questioned.