Life after surviving cancer

Amit Bhavsar seeks answers to why chemotherapy toxicities, like loss of hearing, affect some patients and how this can be prevented

Medical science has made huge progress in the treatment of childhood cancer, with the five-year survival rate now almost 80 per cent. While that is cause for celebration, this achievement sometimes comes with a terrible downside.

Many childhood cancer survivors suffer from serious health complications, ranging from deafness to cardiac issues, due to toxicities associated with chemotherapy. Amit Bhavsar is leading a team working to understand the biological processes that result in these adverse drug reactions. The hope is that someday, they will not only be able to predict which patients will be affected by drug reactions, but also develop therapies to prevent them from occurring.

“More kids are surviving cancer and that’s a great thing,” says Bhavsar. But researchers need to understand treatment-related toxicities and work toward preventing them. “This has been a real gap in our knowledge.”

One of the chemotherapies his team is studying is cisplatin, widely prescribed to children with brain, liver and bone cancer. Half the children treated with cisplatin lose their hearing permanently. Hearing loss in the youngest patients affects development of speech, language and social skills. “Imagine going through this horrendous ordeal, surviving cancer, and at the end of it, losing your hearing permanently,” explains Bhavsar.

Doxorubicin, another chemotherapy drug, is an effective treatment for blood cancers in children. But up to 20 per cent of young patients taking it suffer negative impacts on their hearts, sometimes including heart failure, either during or after treatment or later in their lives.

While adults can suffer serious side effects from anti-cancer drugs, treatment regimens in children differ from adults and children’s systems are still developing, making them more vulnerable to toxicities than adults, says Bhavsar.

If toxicities show up during treatment, oncologists have little choice now other than stopping or reducing dosages, which can affect the chemotherapy’s effectiveness. Bhavsar hopes his research will lead to co-therapies that would target and prevent these drug reactions.

Even with advances in genomics, this won’t be achieved overnight. “These things take a long time. But what I hope we’ve done in five years is demonstrate success so that we have the confidence of institutions and funding agencies that really see strength in our research program.”

It’s not only anti-cancer drugs that carry risks for children, as Bhavsar has experienced in his own family. His three boys were all born prematurely and began their lives in a neonatal intensive care unit, receiving medications with known side effects. He and his wife know what it’s like to worry about drug toxicities. Bhavsar hopes his ground-breaking research will eventually have a wider impact beyond oncology.

Amit Bhavsar’s research has been supported by the Stollery Children’s Hospital Foundation through WCHRI.