"In terms of taking care of the patients, that is first and foremost from the physician's side," Dunn said.
While the physician's responsibility is to certify the severity of the inmate's disease, regardless of his or her criminal history or sentence, the ultimate decision for release usually rests with administrative personnel, who consider medical, legal, and social factors involved in each individual case.
Release on this basis, however, does not constitute a pardon, Blackston said.
Clearly, terminally ill patients don't always conform to the expectations. Despite petitioning for release more than a year ago, Atkins is still alive despite her initial prognosis of six months to live.
"Cancer does funny things -- it sometimes gets better for periods of time, but the key issue is if you stop active treatment, if you're no longer able to actively treat a patient, by definition they're terminal," Dunn said.
Indeed, predicting time left can prove a complex enterprise.
"We know there are diseases for which we don't have a cure," said Dr. Brie Williams, an assistant professor of medicine at the University of California-San Francisco, who has worked extensively with inmates.
"For those patients with an incurable condition, prognostication is based on a complicated combination of factors including: disease [for example, metastatic cancer or advanced dementia], functional status [such as whether the patient can eat or get out of bed], social support, and access to medical care," she said. "However, prognostication of death is an inexact science and physicians prognosticate most accurately when death is imminent [in the days, weeks and perhaps months leading up to death].
"The more imminent that death is, the better physicians are at prognosticating, but we are not very good at prognostication when it gets beyond that time frame," Williams said.
But, in general, terminal patients do not tend to live long.
Drs. Nicholas Christakis and Jose Escarce looked at that question in a 1996 study at the University of Chicago. In their article, published in the New England Journal of Medicine, median survival in the 6,451 hospice patients they examined was only 36 days, with approximately 16 percent dying in the first week. Only about 15 percent of these hospice patients were still alive at six months.
Re-enrollment is required by Medicare at six months for further hospice care. For all prisoners, that cost falls to the government.
"The financial responsibility for all medical care for prison inmates is with the state or federal government," Mississippi's Blackston said. "If the patient is discharged from custody, then usually private insurance, Medicaid, or Medicare is relied upon as the payor source."
Surprisingly, a patient like Susan Atkins might actually live longer in prison.
"We would hope that her medical care, while incarcerated, is certainly equivalent to that in the 'private' sector and, in many cases, it may indeed be better, given that if she [or any other incarcerated patient] is released, she may not necessarily have ready access to [the same] high=quality medical care," Blackston said.
Ultimately, some prisoners, like Atkins, are not released, but Texas' Dunn said that when that situation arises, things can still be done.