Almost 10,000 additional cancer patients in England will miss out on timely treatment because the government is on course to fall short of its targets, experts have warned, blaming a failure of leadership, focus and resources.

The NHS set itself an interim goal of treating 80% of cancer patients within 62 days of an urgent referral or consultant upgrade by March 2027. With little more than 100 days remaining, official figures show just 70.7% of patients began treatment on time in September, down from 71.9% in August.

Exclusive analysis of the official data for the Guardian indicates the health service would need to treat a further 2,850 patients on time every month to recover its position, assuming patient volumes stay constant.

Calculations by the charity Radiotherapy UK show 24,400 cancer patients a month would have to start treatment on time to reach the 80% target in March. In reality only around 21,500 are being treated within the 62-day window each month, producing a monthly gap of 2,850 and a cumulative shortfall of 9,490 patients.

Prof Pat Price, chair of Radiotherapy UK and a leading oncologist, said: "The government is going to miss its cancer treatment target because the NHS does not have enough staff or equipment to treat the number of patients coming through its doors. This lack of leadership means thousands more people could die because they don't get their treatment on time."

The analysis also exposed wide variation between cancer types. More than two-thirds of patients with prostate and breast cancers, 70.1% and 68.8% respectively, were treated within two months, but that fell to 60.9% for lung cancer and 60% for gynaecological cancers. For head and neck cancers barely half, 56.5%, were treated on time. Regional gaps were stark too: the Midlands recorded the lowest share treated on time at 66.6%, against 77.3% in London.

Mark Lawler, professor of digital health and chair in translational cancer genomics at Queen's University Belfast, blamed failures of accountability and focus. "The whole system is being held together by goodwill glue alone," he said, warning that without accountability, a radical change of mindset and a focus on the basics, targets could be missed for another decade.

Separate analysis by Cancer Research UK of the latest diagnosis figures found that over the past year only 55.4% of patients with cancer were diagnosed within 28 days of an urgent referral, far below the 80% faster diagnostic standard, while 79.1% of patients received the all-clear on time. Naser Turabi, the charity's director of health policy and evidence, said hospital capacity could not keep pace with demand, with urgent referrals in England up about 20% in four years.

Dr Hilary Williams, clinical vice-president of the Royal College of Physicians, said faster diagnosis only helps if treatment follows quickly, calling for capacity across imaging, endoscopy, pathology, surgery, radiotherapy and systemic treatments. Dr Stephen Harden, president of the Royal College of Radiologists, said "chronic shortages" of radiologists and oncologists were "driving dangerous delays", adding that NHS hiring freezes for these doctors had doubled in the last year and urging the government to end recruitment freezes.

A Department of Health and Social Care spokesperson said cancer waiting times were moving in the right direction, with all three cancer standards better than a year ago and around 290,000 more people diagnosed on time or given the all-clear over the last year compared with the year before the election. The spokesperson added that the national cancer plan would help more people get diagnosed earlier and start treatment sooner, while acknowledging there was much more to do.