Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:
Shift Work Does Not Increase Breast Cancer Risk: Study
Working night shifts does not increase women's risk of breast cancer, a new study says.
Researchers in the U.K. examined data from 1.4 million women and found no association between night shift work and breast cancer, BBC News reported.
The study appears in the Journal of the National Cancer Institute.
In 2007, a World Health Organization committee said studies in people and animals suggested that shift work "probably" had a link to breast cancer, BBC News reported.
Double Arm Transplant for U.S. Marine
A U.S. Marine who had a double arm transplant in the summer is in his second month of rehabilitation and being closely monitored by his medical team for any sign that his body might be rejecting his new arms.
John Peck underwent the 14-hour transplant surgery at Brigham and Women's Hospital in Boston. The procedure involved 60 surgeons, nurses and technicians, CBS News reported.
Peck lost all four of his limbs in an explosion in Afghanistan in 2010.
His new arms came from a young man who was declared brain dead. Peck's own nerves have to grow down to the fingertips of his new arms before he can use them, which could take a year, CBS News reported.
Currently, Peck's new arms are in braces to safeguard them from strain.
Controversial Blood Testing Company Closes Labs
Theranos Inc. is retreating from its goal of offering a wide range of low-price blood tests directly to American consumers.
It announced Wednesday that it will close its blood-testing facilities and reduce its workforce by more than 40 percent, the Wall Street Journal reported.
Theranos has a lab in California and another in Arizona, along with five blood-drawing sites that send samples to the Arizona lab. The California lab has been closed since July when regulators revoked the company's license to operate the facility. That decision is being appealed by Theranos.
Previously, WSJ revealed problems in the Palo Alto, Calif.-based company's technology and operations.
Theranos said it plans to focus on developing products for outside labs.