I want to draw your attention to an exciting study that was recently published online in the Journal of the National Cancer Institute and that is truly deserving of the media attention it has received. (I know some of the researchers at the University of California, San Francisco, who authored this paper, and have been following their work for years.)
Why am I so excited? Well, this is the first time that scientists have discovered biomarkers that appear to predict which women with the pre-cancer ductal carcinoma in situ (DCIS) are most likely to go on to develop invasive breast cancer and which are not.Â In addition they identified a separate group that was more likely to have a local recurrence of DCIS.Â Interestingly these two groups were not the same.
Right now, when a woman is diagnosed with DCIS, she is typically told that she will need to have a lumpectomy, radiation, and possibly five years of hormone therapy. For women with extensive DCIS throughout their breast, the recommended treatment is typically a mastectomy.Â (In addition, some women choose to have a mastectomy even if they could have a lumpectomy.) These treatments are not being given because a woman has cancer. A DCIS diagnosis means the woman is at high risk for developing breast cancer and the treatments are given to reduce that risk.
Weâ€™ve known for some time that many women with DCIS are being overtreated, because we know that, in general, only about 20 to 30 percent of DCIS will go on to become invasive breast cancer if left untreated! But because we have not had any way of knowing which women with DCIS needed treatment, and which did not, doctors recommended that every woman be treated.
The UCSF researchers tried to determine which type of DCIS was most likely to go on to become invasive cancer and thus needed to be treated, by looking at slides that were made from tissue that was taken from 1,162 women aged 40 years and older who had been diagnosed with DCIS years ago and had been treated with lumpectomy alone.
As has been shown many times before, the study found that DCIS that appears as a lump is more likely to become invasive than DCIS that is found on a screening mammogram. More interesting, however, was that the study found that when the DCIS found on mammography contained three biomarkersâ€” p16, cyclooxygenase-2 and Ki67â€”it was more likely to go on to develop into invasive breast cancer within eight years than was the DCIS that did not contain these biomarkers.
Specifically, women whose DCIS was identified by mammography and contained these three biomarkers had a 20% chance of developing invasive cancer, while women whose DCIS did not have these biomarkers only had a 4% chance of going on to develop invasive breast cancer.
The study also identified markers that suggested there were a second group of DCIS patients who were more likely to have their DCIS recur. Since this group had a DCIS recurrence and did not develop an invasive cancer, it could be that they had more extensive DCIS throughout the duct.Â This suggests that it might be possible for this type of DCIS to be watched closely rather than be aggressively treated.
This study was a retrospective study, but because the studyâ€™s findings were so significant they will most likely be tested in a prospective study soon.Â This prospective clinical trial would enroll women who had been diagnosed with DCIS and it might look something like this: Women whose DCIS was detected as a lump or produced biomarkers that showed it was aggressive would be given aggressive treatment, including tamoxifen, radiation, and maybe even mastectomy, while women whose DCIS was detected on mammography and produced biomarkers that showed it was very low risk might have a lumpectomy or five years of tamoxifen, or undergo surveillanceâ€”what we might call â€œwatchful waiting.â€
Bottom line: If you are diagnosed with DCIS tomorrow, these findings wonâ€™t change how you are treated. But I will venture to guess that in 10 years (or less) they probably will!