NHS cancer services are struggling with widespread shortages of specialist nurses who give patients drugs, help them through their illness and care for those who are dying, a report reveals.

Hospitals in England have vacancies for more than 400 specialist cancer nurses, chemotherapy nurses, palliative care nurses and also cancer support workers, raising doubts about the NHS’s ability to cope with the fast-growing number of people being diagnosed with the disease.

Macmillan Cancer Support, which undertook the research released on Monday, warned that cancer patients were losing out, with some forced to wait to receive chemotherapy, while cancer nurses were being “run ragged” as they were forced to take on heavier workloads because of rota gaps.

“Having the expertise and support of a specialist nurse from the point of diagnosis has a huge bearing on whether or not a cancer patient has a positive experience of the care they receive.

“We are concerned that cancer nurses are being run ragged and that some patients may not be receiving the level of specialist care they need,” said Dr Karen Roberts, Macmillan’s chief of nursing.

“If there aren’t enough specialist cancer staff in place to cope with ever-increasing demand, then all too often it is patients who face the consequences. Patients can really struggle during and after treatment if they do not have enough expert support. Worse still, access to the badly needed treatment may be reduced or delayed if there are shortages of highly trained chemotherapy nurses,” she added.

Across England, the NHS is short of 166 specialist cancer nurses, 158 chemotherapy nurses, 44 palliative care nurses who treat cancer patients, and 61 cancer support workers, a total of 429 posts, according to staffing information supplied to Macmillan by lead cancer nurses in hospital trusts.

Some of the biggest holes in the cancer workforce are in the Thames valley, which includes Theresa May’s Maidenhead constituency. It is 15 chemotherapy nurses short of the 113 it should have, a vacancy rate of 15.1%, which is the second highest in England behind the 15.3% shortage in the Peninsula cancer alliance area in Devon, according to MacMillan research.

Similarly, the Thames valley is also lacking nine specialist cancer nurses. That is the joint third highest vacancy rate (7%) in the country alongside Cheshire and Merseyside, which has 16 vacant posts (7%), behind north-west and south-west London (30 vacancies – a 10.8% vacancy rate) and north-central and north-east London (15 vacancies or 7.4% of the workforce).

In January, it emerged that the Churchill hospital in Oxford was considering delaying patients’ access to chemotherapy, and restricting the number of cycles of the potentially life-saving treatment that even the terminally ill could have, because its chronic shortage of cancer nurses meant it had too few staff to administer the drugs.

“It’s no exaggeration to say that the shortage of nurses is putting patients’ lives at risk. As we saw earlier this year, not having enough specialist staff available can delay, or reduce, access to treatment, including life-saving chemotherapy,” said Ann McMahon, the Royal College of Nursing’s research and innovation manager.

The shortages mean that specialist nurses in some parts of England are looking after 251 patients newly diagnosed with prostate or bladder cancer a year while others take on 87 new cases. Similarly, some breast cancer nurses are seeing 145 new patients a year while others get 56 fresh cases.

Overall, though, the cancer workforce has grown since 2014, the research shows. For example, there are now 4,020 specialist cancer nurses, compared with 3,088 then. However, Macmillan said staffing was not growing fast enough to keep up with the rapid increase in people being diagnosed with cancer. Cancer Research UK has estimated that ageing and lifestyle factors mean that the number of people diagnosed with the disease in the UK will rise from 352,000 to 500,000 cases a year by 2035.

Jonathan Ashworth, the shadow health secretary, said: “It is totally unacceptable that cancer patients are not receiving the specialist care they need because of this government’s failure to plan the NHS workforce. We should be giving patients who are fighting cancer the best possible support and that means services which are properly resourced and properly staffed.”

The Department of Health and Social Care declined to comment directly on the vacancies. A spokesperson said: “Cancer survival rates are at a record high, with around 7,000 people alive today who would not have been if mortality rates stayed the same as in 2010. As well as expanding nurse training places by 5,170, we are also committed to increasing the capacity and skills of specialist cancer nurses.”