The HSE has estimated up to 2,000 cancer diagnoses have been missed due to the impact of the Covid-19 pandemic.
The health service analysed the number of patients diagnosed through its rapid access clinics for breast, lung and prostate cancer.
Some 371 fewer cases have been diagnosed through these clinics so far in 2020 compared to 2019.
The clinic typically finds 21 per cent of cancer cases in Ireland each year.
Dr Risteárd Ó Laoide, director of the National Cancer Control Programme, urged people with symptoms to contact their GP.
“Under the law of averages we should have that number of cancer cases, and we haven't had it – so they're somewhere,” he said.
“We want anyone with any suspicion or worry about cancer to come forward, they will be seen.”
Earlier this month it was revealed that more than 300,000 cancer screenings have been delayed during the crisis.
Figures obtained by The Irish Examiner showed the BreastCheck and BowelScreen initiatives were more than 70 per cent behind 2020 targets, while CervicalCheck was 63 per cent behind.
