ADVANCES in cancer treatment which allow people to survive the disease for longer are piling pressure on the NHS, one of Scotland's leading oncologists has said.

Dr David Dodds said patients were living longer thanks to "world-class radiology" and breakthrough cancer drugs, but stressed that facilities and staffing levels had lagged behind.

Dr Dodds, the former clinical director of the Beatson West of Scotland Cancer Centre, the UK's second busiest cancer hospital, said it had been easy to predict that cancer incidence would increase as the population aged, but that the impact of therapies that allow more patients with incurable cancer to survive for years had come as a surprise.

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He said: "The major difference in cancer care over the last 10 to 15 years has been a move from a condition that used to be regarded as terminal to one which can be controllable for a large period of time. It's moving out of the realms of an acute illness to one of a chronic condition which can be managed and maintained in some patients for a large number of years.

"In the past, if I had metastatic cancer I would have maybe six or seven shots of chemotherapy and that would be it.

"But with the new treatments, especially immunotherapies, they're given until disease progression. So I might have to turn up every three weeks for one year, two years, three years - however long it takes for the cancer to develop a resistance and deteriorate. That means patients are coming in a lot more often, so not only are there more patients as a result of ageing but the patients we have are coming in more often and there's no end in sight potentially, until disease progression.

"That creates a huge strain on the existing resource. We need more of everything - oncologists, cancer nurses, radiologists - in order to cope. The numbers that are passing through our day-case units in our outpatient departments are increasing logarithmically right now. That's great for patients, but it's not great for staff because staff numbers have not increased in a commensurate way."

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Clinical radiologists have the highest vacancy rate of any medical specialism, with 14 per cent of post unfilled. Waiting times for cancer tests and treatment have also been increasing steadily since 2012 amid increasing demand.

Dr Dodds, who is now the chief of medicine for regional services in NHS Greater Glasgow and Clyde, was speaking ahead of a new three-part BBC Scotland series 'The Cancer Hospital' which goes behind the scenes at the Beatson.

The series focuses on breast, prostate and lung cancer through the individual stories of patients including Jasmine Smith, who was diagnosed with stage 4 breast cancer aged 24, and 52-year-old Lesley Stephen who has lived with stage 4 breast cancer for more than two years thanks to an experimental new drug she received as part of a clinical trial.

Dr Dodds said he was optimistic that new innovations, especially in relation to personalised medicine and immunotherapy, would continue to improve and extend survival rates from cancer.

Personalised medicine tailors treatments to individual patient's tumour characteristics at a genetic level, while immunotherapy works by supercharging the patient's own immune system to attack cancer cells.

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Dr Dodds said: "That's where I think the significant advances will be made and have already started to be made in some tumour types over the next five to 10 years.

"Already you see with some breast cancers we're looking at some genetic characteristics and tailoring the treatment individually according to those characteristics. In some colorectal cancers it's exactly the same process.

"In some melanoma and kidney cancers, immunotherapy it is starting to take over from chemotherapy. Immunotherapy is evolving rapidly at the moment and there are a number of different tumour types where there are trials actively ongoing to look at the possibility of improving survival, as has happened with melanoma and kidney cancers."