Allowing patients to "top up" their care with privately bought drugs not available on the NHS is the only realistic way forward, according to a Commons health committee report.
This is despite concerns that the new system may create a two-tier health system and be difficult to put into practice.
The committee says: "We believe it would be wrong for very seriously ill patients to be moved from an NHS ward to a different location so as to administer a privately paid-for drug separately.
"This undoubted disruption to a person's quality of life just to meet some bureaucratic requirement would not only endanger the patient's care, but would be unjust."
After a review by government cancer expert Professor Mike Richards, a ban on people who buy their own drugs from receiving state care is now being relaxed.
The report concludes: "Although we are not convinced by the arguments that dismiss the threats of establishing a two-tier system or that separation of patients is practicable for only a part of the treatment, we can see no transparent way of alleviating the problem other than Professor Richards' proposals."