Patients with an early form of breast cancer are less likely to suffer a recurrence if they are post-menopausal or if their tumour is oestrogen receptor positive, according to research presented at the 11th European Breast Cancer Conference.
Although ductal carcinoma in situ (DCIS) is a non-invasive form of breast cancer, it can become invasive.
Because little is known about which cases will progress, DCIS is treated in much the same way as other forms of breast cancer.
The new study shows that treatment including removal of the cancer followed by radiotherapy to the affected breast leads to very low rates of recurrence.
Researchers say the study also offers clues as to which patients need more aggressive treatments, and which could safely have fewer treatments.
The research was led by Dr Icro Meattini, a clinical oncologist at the University Hospital of Florence, Italy.
He said: “A diagnosis of DCIS can be frightening but also confusing. Although we know that very few patients will go on to develop invasive cancer, we don’t know which ones they will be and so we offer treatments such as surgery and radiotherapy, and sometimes hormone therapy.
“We wanted to look in detail at women treated for DCIS to see if there are any clues about who is most at risk of a recurrence, and to understand the risks and benefits of different treatments.”
DCIS accounts for about 20% of breast cancer cases.
Although mortality rates are very low, DCIS can recur and around half of recurrences are invasive cancers.
Dr Meattini and his colleagues studied 1,072 DCIS patients treated at nine hospitals in Italy from 1997 to 2012.
All had received the recommended treatment of breast conserving surgery followed by radiotherapy.
Researchers compared the rate of recurrence five years and ten years after diagnosis, as well as survival rates.
Overall, they found that patients had a 3.4% risk of a recurrence after five years and a 7.6% risk after ten years.
They also found that patients’ chances of dying from breast cancer were 0.7% after five years and 0.9% after ten years.
They found that patients who were post-menopausal when they were diagnosed were less likely to suffer a recurrence compared to pre-menopausal patients.
Recurrence was also less common among patients with oestrogen receptor positive cancers (cancers that are stimulated to grow by the hormone oestrogen).
Being post-menopausal and having oestrogen receptor positive DCIS halved the risk of a local recurrence.
On the other hand, patients with a final surgical margin of less than a millimetre had a three times higher risk of recurrence.
This means that when the cancer was surgically removed, the surgeon was unable to remove a wide margin of non-cancerous tissue around the tumour.
“The results of this study should offer all DCIS patients reassurance that the risk of their cancer returning is very low, if they are treated with breast conserving surgery followed by radiotherapy.”
Dr Meattini added: “The results of this study should offer all DCIS patients reassurance that the risk of their cancer returning is very low, if they are treated with breast conserving surgery followed by radiotherapy.”
“For patients who are post-menopausal or whose cancer is oestrogen receptor positive the likelihood of recurrence is even lower. Where the results of surgery reveal very small cancer-free margins, the risk of recurrence is higher.”
“Now we need to do more research to find out if lower-risk patients can safely be given less treatment or even no treatment, as well as studies on how best to treat higher-risk patients. In the meantime, it’s vital that each patient receives treatment that is best suited to their individual cancer and their particular circumstances.”
Professor Isabel Rubio is co-chair of the 11th European Breast Cancer Conference and Director of the Breast Surgical Unit at Clinica Universidad de Navarra, in Madrid, Spain, and was not involved in the research. She said: “Thousands of women are diagnosed with DCIS every year. Although it is non-invasive, a proportion of patients will go on to develop invasive breast cancer, so surgery and radiotherapy are usually recommended.”
“This study provides more reassurance to patients that their risk of recurrence is low. It also provides doctors with more information on which patients have a higher chance of a recurrence, and points the way to further research on how to tailor treatments to individual patients.”