Patients with prostate cancer, which kills 10,000 men in England every year, are treated unfairly and are seen as a low priority, MPs have said.
Ministers acknowledged improvements were needed
The government has been urged to improve services across the NHS by the Commons public accounts committee.
MPs also said that while there had been improvements, many patients in England with suspected cancer were still waiting too long to see a specialist.
Ministers said work was being done to "maintain the momentum of improvement".
Committee chairman Edward Leigh said: "Prostate cancer... is regarded as a lower priority than other common cancer when it comes to the provision of specialist care.
"The inequitable treatment of this group of NHS patients is entirely unacceptable."
The committee urged the government's cancer tsar to publish an in-depth report on the standard of prostate services in England and the reasons for any deficiencies.
Action plans for improvements should be set in motion where there are problems, MPs added.
A Department of Health spokesman denied prostate cancer was a lower government priority, saying it was just that NHS guidance came at a later time.
"We are currently working very hard towards establishing specialist teams for prostate cancer, each with a nurse specialist to provide the care and support that people need."
Chief executive of the Prostate Cancer Charity John Neate said the committee had "shone a searching light" on the problem and he urged the government to act quickly.
"There are major gaps - reinforced by our own research - in the care, quality and consistency of information [patients] get, as well as support during what, for many men, is a time of great anxiety and complex decision making."
Prostate cancer kills 10,000 men in England yearly
The committee was responding to National Audit Office research on progress in cancer services between 1999 and 2004, which also found 40% of cancer patients waited more than two weeks to see a specialist.
The public accounts committee also said waits should be no more than two weeks and that GPs needed to improve their ability to identify patients with cancer symptoms.
MPs also singled out:
The uneven spread of palliative care beds
The lack of information given to patients on drugs' side-effects and pain linked to their condition.
The lack of information on financial benefits on offer to cancer patients
A spokesman for cancer support charity Macmillan Cancer Relief said the officials must ensure every patient gets specialist benefits advice.
"The government must address these issues by producing a new National Cancer Plan which goes beyond tackling waiting lists and death rates," the spokesman added.
This call was mirrored by Derryn Borley of support charity CancerBACUP.
She added: "Many of the callers to our helpline are worried about the length of time they have to wait for their diagnosis and treatment, or the fact that they haven't been given enough information."
Health Minister Rosie Winterton said the report acknowledged improvements in services between 2000 and 2004.
She said patients were seeing the benefits of more staff, modern equipment and shorter waiting times.
"More lives are being saved as a result - death rates have fallen by 14% since 1996.
"The report also recognises that there is more work to be done. We acknowledge this and have put actions in place to maintain the momentum of improvement."