WATERLOO -- The COVID-19 crisis could lead to a "shadow pandemic" of mental health issues and a "tsunami of cancer" from missed screening appointments, a Waterloo region physician says.

Speaking at the region's weekly COVID-19 briefing, Dr. Sharon Bal, a primary care physician who works with Waterloo region's vaccine distribution task force, said the pandemic has had a major impact on hospital care locally and provincially.

Health officials in Ontario have said the pandemic-induced surgical backlog is more than 250,000 procedures.

Dr. Bal said that figure is likely three to five times higher when tests, diagnostic procedures and more are factored in.

"That's upwards of a million procedures or tests or cancer screenings that have been delayed because of COVID," she said. "In spite of the term elective surgery, all surgeries are somewhat mandatory, so that is a concern."

A cancer screening backlog could also lead to a "tsunami of cancer," Dr. Bal warned, as many tests have been cancelled or postponed amid the COVID-19 pandemic.

"We are at risk of losing massive gains we've made in early detection of cancer if we're not careful," she said.

Although most cancer screenings were cancelled in the first wave of the pandemic, Dr. Bal said many have since resumed.

"Cancer does not wait for COVID," she said.

The pandemic has also triggered a "staggering" increase in the intensity and acuity of mental health issues, Dr. Bal explained.

"We are seeing people who have not traditionally sought mental health (support)," she said. "The message is really please seek help early."