New research, which raises the possibility that a particular form of breast cancer is being over-treated, will not change standard practice in Ireland, a leading breast cancer surgeon has said.
Mr Terry Boyle, consultant breast surgeon at St James’s Hospital in Dublin, said the US research would not alter the established standard of care for ductal carcinoma in situ (DCIS).
For the majority of women this involves a local excision of the diseased tissue with or without radiotherapy.
“In general terms, DCIS is a pre-invasive condition and not breast cancer per se. However, there is no role at present for simply observing a woman with DCIS,” he said.
He was commenting on one of the largest studies of DCIS ever carried out, which followed some 100,000 women for 20 years.
It found no significant difference in mortality from the cancer between women treated for the disease and the general population.
The standard surgical treatment for DCIS is either a local excision of the diseased tissue, called a lumpectomy, or a mastectomy where the entire breast is removed.
The research, published in the medical journal JAMA Oncology, found the difference in survival among women who had mastectomies or lumpectomies was not significant.
Their chance of dying of breast cancer in the two decades after treatment was 3.3 per cent, no matter which procedure they had.
The study also revealed that women under 40 and those of African-American ethnicity are at risk of a more aggressive form of DCIS.
The diagnostic rate for DCIS has increased in the past two decades and it now makes up about a quarter of screening-detected breast cancers.
This is because mammography is picking up ever smaller lesions as scanning technology improves.
Dr Otis W Brawley, chief medical officer at the American Cancer Society, suggested that current treatment regimes should continue until a large clinical trial is done that randomly assigns women to receive mastectomies, lumpectomies or no treatment for DCIS.
Only then could a no-treatment option be considered, he said.
A linked editorial suggested that DCIS may represent an opportunity to alter the environment of the breast.
“For the lowest-risk lesions, observation and prevention interventions alone should be tested. Diet, exercise, moderate alcohol intake, and avoidance of postmenopausal hormone therapy with progesterone-containing regimens should be the starting point for prevention,” it said.
Analysis: Research poses more questions than it answers
While adding to our knowledge, in many ways the study of a particular form of breast cancer published last week in the medical journal JAMA Oncology poses more questions than it answers.
The extensive analysis of data on ductal carcinoma in situ (DCIS) raises the possibility that women who are treated for the condition are no less likely to die of breast cancer than women on average.
Being diagnosed with DCIS means that cells inside some of the milk ducts in the breast have started to turn into cancer cells.
These cells are all contained inside the ducts and have not started to spread into the surrounding breast tissue or anywhere else in the body.
Some doctors consider DCIS a premalignant condition; the debate about the exact significance of the diagnosis has led to various terms to describe it, including pre-invasive, non-invasive, ductal intraepithelial neoplasia (DIN) or intra-ductal cancer.
Surgery is the main treatment for DCIS. Many women have the area of DCIS removed, with a border of healthy tissue around it. This is called wide local excision or lumpectomy.
After wide local excision surgery, radiotherapy to the rest of the breast tissue may be recommended if the DCIS cells look very abnormal when examined under a microscope.
And some women opt for a full removal of the breast (a mastectomy).
What the analysis of some 100,000 women with DCIS, followed for 20 years, showed was that the difference in survival between those who had mastectomies and lumpectomies was not significant.
Their chance of dying of breast cancer in the two decades after treatment was 3.3 per cent, no matter which procedure they had.
As an accompanying editorial in the journal noted, this is about the same as an average woman’s chance of dying of breast cancer.
However, the study did find that women under 40 and African-American women were at higher risk.
Adding to the conundrum is the fact that as the technology behind mammography improves, the DCIS diagnosis rate has risen from about 3 per cent before breast-cancer screening became available to some 20 to 25 per cent of screening-detected breast cancers now.
Here are some of the key questions raised by the paper: should much of DCIS be considered a risk factor for invasive breast cancer rather than a fully-fledged cancer in its own right?
Should radiotherapy become less routine after a lumpectomy for low risk DCIS lesions?
Or does DCIS have more in common with invasive cancers than previously thought?
Where does this leave a woman newly diagnosed with DCIS? Until there is definitive research that shows treating DCIS is unnecessary, most women, in consultation with their oncologists, should consider at least having a lumpectomy for the condition.
