Figures released by Public Health Scotland last week have revealed a drop in the number of cancer diagnoses in 2020, compared to 2019, across the south of Scotland.
In NHS Dumfries and Galloway, numbers dropped from 1,115 in 2019 to 1,008 in 2020.
In Ayrshire and Arran, the numbers fell from 2,492 to 2,313, and NHS Borders noted a drop from 766 to 714.
Many clinics and services were halted in 2020 as the NHS battled the pandemic.
Mr Smyth said: “These figures lay bare the scale of the devastation the pandemic inflicted on cancer services in Scotland.
“Early detection is key to saving lives, but that went out the window in 2020.
“We know that the incidents of cancer are growing and are projected to double between 2010 and 2030. So, the fact the number of diagnosis is falling means there are more and more people out there who have cancer, but don’t know it.
“The Scottish Government have had one warning after another about this, but have continually buried their heads in the sand.
“This dangerous complacency is costing lives and causing the chaos we see in cancer services now.
“Lives are at stake here – we urgently need a real catch-up plan that includes Labour’s proposals for rapid diagnostic centres, to save lives and deal with this ticking timebomb of cancer cases.”