The researchers asked breast cancer patients specific questions about the grade, stage and subtype of their tumor.
This is thought to be the first study to find out how much patients understand about their particular cancer as opposed to cancer in general.
The researchers say the findings show there is a gap in patient education.
Helping patients understand their condition has many benefits, not least in making better informed treatment decisions, reducing the risk of developing new conditions and taking care of general health.
For the study, Rachel Freedman, a physician at the Dana-Farber Cancer Institute and Assistant Professor of Medicine at Harvard Medical School, Boston, MA, and colleagues surveyed 500 women with breast cancer.
The women were asked questions about the grade, stage and receptor status (the cancer subtype) of their breast cancer.
The results showed that while 32-82% said they knew each of the tumor characteristics they were asked about, only 20-58% could actually specify them correctly.
White women seem more knowledgeable about their particular breast cancer
White women were more likely to know the features of their cancers than black or Hispanic women. This was the case even when the researchers corrected for potential influencing factors such as health literacy and socioeconomic status.
However, they found health literacy and educational attainment did explain some of the knowledge gaps in Hispanic women but health literacy had little effect on the findings for black women.
Prof. Freedman says their findings show there is a lack of understanding among many patients about their particular cancers. She notes that the study identifies a "critical need for improved patient education and provider awareness of this issue," and adds:
"Improving patients' understanding about why a particular treatment is important for her individual situation may lead to more informed decisions and better adherence to treatment."
Increased knowledge about her condition and the particular features of her own tumor will also help a woman understand the reasons behind a particular personalized therapy.
This can increase trust and confidence, as well as satisfaction, with the professionals providing her care and treatment, say the researchers.
According to the American Cancer Society (ACS), there are currently about 2.8 million breast cancer survivors in the US. However, while death rates of the disease among American women have been falling since 1989, breast cancer is still the second leading cause of cancer death in women, exceeded only by lung cancer.
The chance that breast cancer will be the reason for a woman's death in the US is about 3% - or 1 in 36 - say the ACS, whose estimates show that about 40,290 women will die from breast cancer in 2015.
Meanwhile, Medical News Today recently learned about a JAMA study that found racial disparities in diagnosis and survival rates of breast cancer in the US. The researchers discovered that the chance of being diagnosed with breast cancer in the early stages, and the chances of surviving after such a diagnosis, may be influenced by race and ethnicity, and that biological differences may be a key factor.