The world's first international clinical guidelines for preventing and treating heart problems in cancer patients' children have been developed.

The guidelines, published in JACC: Advances, address cardiovascular disease assessment, screening, and follow-up in pediatric cancer patients receiving novel molecular treatments, immunotherapy, chemotherapy, and radiotherapy.

The Murdoch Children's Research Institute-led expert consensus defined the high-risk group of cancer patients who should have a heart check-up, standardised a strategy for screening and surveillance during treatment, and provided recommendations to protect vulnerable young hearts.

Murdoch Children's associate professor Rachel Conyers said while international guidelines to monitor poor heart side effects during therapy exist for adult patients, none were specific to children.

Associate professor Conyers said the success of new cancer drugs had increased the chances of cardiac side effects that occur early on during therapy, sometimes within days, which warranted closer heart health surveillance and earlier monitoring.

"Recent advances in treating childhood cancer have resulted in survival rates of more than 80 per cent. However, improving serious health outcomes in survivors remains an important and essential focus and prevention is key," she said.

"Heart complications are a leading cause of death for childhood cancer survivors, second only to cancer relapse. Modern treatments including precision medicine have broadened the agents that can cause heart problems," she said.

Childhood cancer survivors are 15 times more likely to have heart failure and eight times more likely to have heart disease than the general population.

Associate professor Conyers said the guidelines would be an indispensable tool for clinicians to significantly reduce the harmful impact of cancer drugs on children's hearts.

"The guidelines are a major advance for the cardio-oncology field as before this there was no defined approach for surveillance or follow up of paediatric patients during treatment despite new therapeutics having early heart complications such as high blood pressure, abnormal heart beats and heart failure," she said.

The Australian and New Zealand expert group consisted of paediatric and adult cardiologists and paediatric oncologists who undertook a Delphi consensus approach across 11 areas of cardio-oncology care.

The Australian New Zealand Children's Oncology Group endorsed the study with the guidelines useful for any tertiary institutes treating paediatric oncology patients or initiating cardio-oncology clinics.