Tackling obesity is now the biggest challenge to the prevention of new cancers, with between 15-20% of cancer diagnoses weight-related, a medical oncologist has said.

Consultant Medical Oncologist at Cork University Hospital Professor Seamus O'Reilly was speaking on World Cancer Day.

He said we have moved from the "tobacco and cancer century" into the "obesity and cancer century".

Speaking on RTÉ's Morning Ireland, Prof O'Reilly said that screening programmes have led to an overall reduction in deaths from cancer.

In particular, cervical, breast and colorectal cancer screening has led to improved outcomes, he said.

However, access to cancer care - particularly for poorer people - remains a huge problem, Mr O'Reilly added.