During the study, researchers found that patients in distressed marriages had higher levels of stress, less physical activity, slower recovery and more symptoms and signs of illness than did similar patients who reported good marriages.
"The quality of the marital relationship may not be the first thing women worry about when they get a cancer diagnosis. But it may have a significant impact on how they cope physically and emotionally," said Hae-Chung Yang, co-author of the study and research associate in psychology at Ohio State University.
"Our results suggest that the increases in stress and other problems that come with a distressed marital relationship can have real health consequences, and lead to a poorer recovery from cancer," Yang added.
The study involved 100 women who have participated in the long-running Stress and Immunity Breast Cancer Project at Ohio State. All of the women were married or cohabitating at the time they entered the study and remained so during the five years they were followed.
Participants completed a questionnaire that measured the quality of the relationship they had with their spouse every year for the five-year study period.
The majority of participants reported very little change in marital quality over the course of the study and, based on these results, they were split into two groups - those who had a distressed relationship (28 women) and those who did not (72 women).
Participants were regularly measured on levels of cancer-related stress and overall stress, diet, physical activity, general physical functioning, and symptoms and signs of illness.
Yang said that the results showed that women with good marriages had plenty of advantages. Women in both groups started the study with high and nearly equal levels of cancer-related stress.
In terms of overall stress, women in distressed marriages saw levels remain stable over the five years, while those in better relationships experienced a steady decline in stress levels.
Women with strong marriages had better dietary habits than those in distressed relationships, and that continued through the course of the study.
Women in strong marriages also maintained adequate levels of physical activity for a longer period of time compared to the women with distressed relationships, whose physical activity dropped steadily.
As far as overall health performance, women in bad relationships saw a significantly slower recovery than did other women.
The study appears online now, and will be published in a future issue of the journal Cancer.