Why Would Some Cancer Tumours Become Resistant to Chemotherapy?

 by Ashnah Elanchcheliyan

Chemotherapy is treatment that uses powerful drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Systemic drug treatments (chemotherapy) are common for stage 4 cancers. As well as killing cancer cells, chemotherapy can damage some healthy cells in your body, such as blood cells, skin cells and cells in the stomach. This can cause a range of unpleasant side effects. 

Resistance can occur when cancer cells undergo molecular changes that make them insensitive to a particular chemical / drug before the treatment even begins. Scientists and researchers from the Garvan Institute of Medical Research found that the tumours’ ability to respond to the chemotherapy given, is driven by randomness. The scientists also say they found that mixing chemotherapy with other drugs can make it more effective against cancer cells that would become resistant in the future. 

Chemotherapy may affect people in different ways. People may only receive chemotherapy, while others may receive chemotherapy in addition to other treatments such as radiotherapy and surgery. There are a number of different elements that may impact how successful the treatment of chemotherapy is to that person: the location of the tumour, the type of cancer, the stage of cancer, and the patient’s age and health. There is a difference in some of the tumour cells and how sensitive or resistant they are to a particular drug (this is called heterogeneity) – this exists in all tumours. There are cells within that are genetically different and the expression of certain genes may also make it sensitive or resistant to a certain drug.

Scientists reported that once a cell becomes resistant to chemotherapy, it stays that way. This suggests that there is a small window where treatment could be most effective. Through pre-treating / priming neuroblastoma tumours with a certain class of drug (called an HDAC inhibitor), it could restore drug sensitivity to otherwise resistant cells. These drugs would be given to the patient before treatment of chemotherapy, to improve the ability of the tumours to respond to the treatment. This may highlight the fact that doctors need to do more combination therapies. This may help to understand what makes a tumour cell resistant to the current chemotherapy.