WASHINGTON – Mary Berry Gerwin, 46, deputy assistant secretary of defense for health program integration and external affairs and a longtime Senate staff member for Maine Republican William S. Cohen, died of breast cancer Sept. 18 at George Washington University Hospital after living with the disease for nine years.

A native of Portland, Maine, Gerwin joined Cohen’s Senate staff in 1981. During her 16-year career on Capitol Hill, she held increasingly responsible positions, including chief of staff for the Senate Special Committee on Aging and Republican staff director and chief counsel for the Senate Subcommittee on Oversight of Government Management.

When Cohen became secretary of defense, Gerwin soon joined him as senior adviser to the assistant secretary of defense for health affairs before being named deputy assistant secretary in 1999. In addition, she served as assistant chief of staff to Cohen. She also received the Secretary of Defense Medal for Outstanding Public Service.

At the Pentagon, she worked to ensure delivery of health care to service members and their families, and concentrated particularly on working to improve health benefits for military retirees. Among her duties was liaison with military family organizations and congressional defense committees. She traveled to the Middle East, Korea and Bosnia to meet with U.S. military personnel about health care and quality-of-life issues, including visits to refugee camps in Kosovo to help improve conditions there.

During her years of working in the Senate, she was instrumental in the drafting and passage of numerous pieces of legislation, including Social Security disability insurance reforms, landmark health care anti-fraud and abuse legislation, consumer protections for nursing home patients, the Independent Counsel Act, Ethics in Government Act amendments, and a major revision of the Clinical Laboratories Improvement Act, as well as procurement and information technology reforms. She was particularly proud of Aging Committee hearings in 1995 and 1996 that led to significant increases in funding for biomedical research into diseases like Alzheimer’s and Parkinson’s and spinal cord injuries.

Gerwin spoke frequently at conferences and other public forums about health care and other issues. She served as a board member and president of the Senate Employees Child Care Center and on the volunteer board of National Rehabilitation Hospital, and she did volunteer work for So Others Might Eat.

Gerwin graduated from the University of Maine summa cum laude in 1977 and cum laude in 1980 from the Georgetown University Law Center, where she was editor of the Tax Lawyer Law Review and where she met her husband, Edward F. Gerwin, now a partner at Winston & Strawn. She was a member of the District of Columbia Bar and the Health Section of the D.C. bar.

She is survived by her husband of 21 years and their two daughters, Katie and Kristen, all of McLean, Va.; her mother, Margaret Berry, a brother George, and a sister Donna, all of Portland; and a sister Theresa Ream of Lewiston, Maine. She also was the daughter of the late George Berry.