A report commissioned by the charity Cancer Research UK found that demand for endoscopies will rise by 750,000 by 2020 - up 44% from current levels.
But the NHS is currently failing to meet rising demand for access to diagnostic tests, with waiting times increasing and patients forced to wait longer than they should.
Research carried out for the charity found understaffing in diagnostic services, shortages of imaging equipment, and equipment that was outdated and in need of replacement.
NHS cancer plan
The findings cast doubt on the viability of the NHS cancer plan unveiled earlier this year, which called for GPs to have greater access to diagnostics to meet a goal for 95% of patients referred by GPs to have cancer diagnosed or ruled out within four weeks.
Earlier this year the RCGP also warned that diagnostics services could be swamped by NICE advice that lowered the threshold for GP cancer referrals.
A second report produced for the charity found that it could cost £215m to replace ageing imaging equipment and more to cover the cost of additional equipment to cope with rising demand.
Sara Hiom, Cancer Research UK director for early diagnosis, said: 'The state of NHS diagnostic services is deeply concerning – and new GP referral guidelines from NICE mean that even more patients will be waiting for these tests.
'There aren’t enough trained staff, they’re often reliant on outdated equipment and in many cases they’re already operating services seven days a week. GPs do not have the access they need and that means patients are waiting too long for tests. This has to change if doctors are to diagnose more people with cancer earlier, when treatment is more effective.'