On October 16, Attorney General Dominic Grieve announced he intended to apply to the High Court to overturn the discredited "accidental death" verdicts and order fresh inquests into the deaths of the 96.
But he conceded that Kevins inquest was unlikely to be brought forward.
A spokesman for his office said: "The Attorney General is deeply saddened to hear of Anne Williams' diagnosis.
"He has written to Mrs Williams saying that he will make the application for a fresh inquest as soon as he can. This work is being given the highest priority.
"If that application is successful, the timing of any inquests is outside his control.
"That is a matter for the coronial process.
"He has considered whether he could make the application sooner if he dealt with Kevin's death only, with a later application for the other deaths.
"Unfortunately given that all the deaths arose from a single chain of events and so much of the evidence applies to all the cases, he does not think that is possible."
Mrs Williams has previously submitted three applications for a new inquest to the Attorney General, all of which were refused.
She has fought relentlessly against the coroners findings that Kevin died before the imposed 3.15pm cut-off.
Debra Martin, a police officer on duty at Hillsborough, told Ms Williams that she had cradled her son at 4pm before he fell unconscious.
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