From the symptoms described in Roots: The Next Generation, I would assume it was Ovarian or Uterine Cancer.
1967
Helen Palmer - archer - was born in 1974.
Renzo Palmer died on June 4, 1988, in Milan, Lombardy, Italy of cancer.
Helmut Palmer died on December 24, 2004, in Tbingen, Baden-Wrttemberg, Germany of cancer.
Maria Palmer died on September 6, 1981, in Los Angeles, California, USA of cancer.
Reese Palmer died on October 27, 2011, in Clinton, Maryland, USA of prostate cancer.
her name was Helen Palmer
Helen Palmer Geisel was born on 1899-09-11.
Helen Palmer - publisher - was born on 1917-05-09.
Elida Gay Palmer died on April 16, 1995, in Buenos Aires, Argentina of cancer.
Helen Vita died on February 16, 2001, in Berlin, Germany of cancer.
Helen Palmer died on 1967 at the age of 68, a month after her 68th birthday