The 73-year-old Oscar-nominated actress, who also starred in Easy Rider and Airport 1975, was diagnosed with ampullary cancer in November 2010 and had a third of her pancreas immediately removed, her husband, Stephen Eckelberry, wrote on the "Help Karen Beat Cancer" GoFundMe website.
Though she was declared cancer-free in 2011, Black – now "mostly bed-bound" and down to 96 pounds, says her husband – relapsed and underwent two more operations in the last year.
The couple is asking for donations to fund a two-month experimental treatment in Europe that is not covered by insurance.
"This is a medically supervised program and it targets Karen's kind of cancer," Eckelberry writes on the site. "We personally know two of the patients that have had remarkable recoveries from cancer there … it is her best and only shot."
As of now, more than $40,000 has been donated, and Eckelberry assures donors their money is going to the right place.
"In the last two years we have used up all of our savings keeping Karen alive," he explains. "Your contribution will cover travel, living and treatment expenses for two months and will give Karen a chance."