Chemotherapy works well for some people or cancers, but not as well for others. Scientists and doctors wonder why.

In fact, researchers at MIT have been studying how certain DNA‑damaging compounds work in different people. They identified forty-eight genes that can predict how susceptible an individual is to the toxic compound known as MNNG.

MNNG is similar to the toxic chemicals found in tobacco smoke and in common chemotherapy agents. MNNG can kill cells by causing irreparable damage to the cell's DNA. That's a good thing if the cell is a cancer cell.

But the researchers found big differences in how susceptible different people's cells are to damage by MNNG. By measuring the response of every single gene in the cells of different healthy people, the team discovered that they could use forty-eight specific genes to accurately predict how each individual's cells would react to MNNG.

The hope is, that this could allow doctors to predict if someone will respond well to chemo by looking at their genes. Although, this study was specific for MNNG, the researchers are now using similar techniques to see if they can also predict individuals' responses to other common toxic agents used in cancer treatments.  Maybe one day doctors will be able to custom‑tailor treatments that best suit each individual patient.