"I never thought of myself as a victim because I refused his advances," Gumpel said. "But my career was a victim."
A Cosby spokesman did not immediately respond to a message seeking comment.
The 77-year-old entertainer faces sexual assault accusations from at least 15 women.
He denies the allegations and has never been charged with a crime.
Gumpel, who lives in Connecticut with her husband, made the allegations at a news conference she held at a downtown Boston hotel hours after Cosby cancelled back-to-back comedy shows scheduled that evening at the nearby Wilbur Theater.
Demonstrators had threatened to protest outside the theatre.
Cosby, who has a home in western Massachusetts, told the Boston Globe he cancelled the shows because of impending "treacherous" weather.
The New England forecast called for a winter storm with nearly 60 centimetres of snow in the Boston area through to Tuesday.
Since the accusations emerged last year, some of Cosby's performances elsewhere have drawn heckling and protests and some have been cancelled.
The Wilbur Theater announced on its website on Sunday morning that the shows were cancelled but did not say why.
It apologised for the abrupt change and said tickets would be refunded.
- AP