A lack of access to diagnostic equipment is hampering a GPs ability to detect the early stages of cancers in 6% of patients.
Ultrasound scanning equipment has been found to be particularly difficult for GPs to access.
The National Audit of Cancer Diagnosis in Primary Care shows people with cancers diagnosed through ultrasound scans are twice as likely (10-12%) than the overall patient population to be faced with longer referral times.
The audit also shows 40% of patients were diagnosed with cancer without having a chest x-ray.
"One in ten patients is a powerful number to encourage a boost in commissioning of testing equipment," said Professor Greg Rubin, Professor of General Practice and Primary Care at Durham University and Project lead for the Audit.
"Commissioning groups will be under considerable pressure but an increase in diagnostic equipment is a priority they need to achieve in the face of difficulties.
"I'm optimistic we will see a difference in the commissioning of testing equipment before too long. It is too high profile not to."
Despite the lack of access to equipment, three-quarters of patients with symptoms of cancer are assessed and referred to specialist care within a month of presenting themselves to GPs.
Furthermore, nearly 60% of all patients referred by GPs attend secondary care within two weeks of their first consultation with GPs.
Dr Clare Gerada, Chair of the Royal College of General Practitioners (RCGP), described the audit findings as "good news" and said it shows "GPs are far from sitting on red flags".
"The evidence is now there to show systematically the NHS works and cancers are being picked up earlier," said Dr Gerada.
However, while emergency presentations for some cancers are said to be "understandable", GPs are being told they "must do better" in other areas – in particular lung cancer as one in five patients currently present as emergency admissions.
Patients with cancer who are housebound and have communication difficulties also have slower diagnosis rates and are 22.9% and 17.1% more likely to present as emergency admissions respectively.
Once housebound and patients with communication difficulties present as an emergency in a secondary care setting, their cancer is likely to be more advanced.
The non-specific and common nature of some cancer symptoms are said to present GPs with the biggest challenge.
"There is a need to encourage people to come to GPs earlier but equally there is a need to raise a GP's awareness of the possibility of cancer in some symptoms linked with those difficult to diagnose cancers," said Professor Rubin.
"Out of 3,000 consultations a year, only 4 of these will be cancer. It is a needle in a haystack."
Looking ahead, it is feared the imposition of "draconian" referral quotas will represent a "serious threat" to the progress being made in the rate of cancer diagnosis in primary care.
"The 2-week referral pathway has been shown to be appropriate and relevant and if enough pressure is applied, there is no scope for a decrease in the amount of referrals," Professor Rubin told MiP.
"The danger is the referral system will become too black and white. GPs will have to have an alternative strategy in place to cope with the growing pressure on referral numbers."
One alternative strategy, he said, is an increase in testing before referral, which could bring down the collective number of referrals "enormously".