The Lanarkshire Beatson, a radiotherapy centre, will treat 80 patients a day for lung, breast, prostate and rectal cancers. It will cater for Lanarkshire and the west of Scotland and will operate as a satellite of the Beatson West of Scotland Cancer Centre in Glasgow.
It is due to open next year.
Cabinet secretary for Health Alex Neil was invited to a ground-breaking ceremony at the site at Monklands General Hospital, in Airdrie, earlier this week.
He said: "We know that going through treatment for cancer can be an extremely difficult time for patients and their families.
"That is why the Scottish Government is determined to see more patients treated in modern facilities - like this state-of-the-art radiotherapy centre.
"I am delighted this vital service is moving closer to being delivered."
Neena Mahal, chairwoman of NHS Lanarkshire, said the development would offer excellent premises for patients from across Lanarkshire and the west of Scotland.
She said it will be equipped with the "most advanced technology and equipment" to deliver "the same world-class treatment currently provided at the Glasgow centre".
She said: "Monklands Hospital is already NHS Lanarkshire's identified cancer centre where we host a number of cancer services.
"The new Lanarkshire Maggie's Centre is also located on the site.
"The radiotherapy satellite centre will be a welcome addition."
The centre will include two linear accelerators to shrink tumours and kill cancer cells, with the potential to expand and house a third machine.
Janette Fraser, project director, said: "It is great to see those plans come to fruition and exciting to think that in around 18 months' time the new centre should be treating patients."
Initially, most patients are expected to come from Lanarkshire but it may take patients from areas such as Forth Valley and Glasgow later.