Young age, DCIS associated with breast cancer recurrence
medwireNews: Young age and the presence of ductal carcinoma in situ (DCIS) adjacent to the primary neoplasm have a negative effect on local breast cancer control, shows the long-term follow-up of a phase III trial.
The EORTC trial, conducted from 1989–1996, randomly assigned women with early-stage breast cancer to either receive no boost or a 16 Gy boost after breast-conserving surgery and whole-breast irradiation. Of the 5569 participants, central pathology review results were available for 1616 – these women were included in the current analysis, which had a median follow-up of 18.2 years.
The cumulative incidence of ipsilateral breast cancer recurrence over 20 years in the study cohort was 15%, with a significant difference between women who did and did not receive boost radiation, at 12% and 17%, respectively.
Multivariable analysis adjusting for treatment and other confounders showed that young age and DCIS were significantly associated with ipsilateral recurrence.
The 20-year cumulative incidence of recurrence was 34% for participants aged younger than 40 years, decreasing to 14% for those aged 41–50 years, and to 11% for women older than 50 years of age.
And the rates for patients harbouring tumours with versus without DCIS were 18% and 9%, respectively, reports the team led by Conny Vrieling, MD, from Clinique des Grangettes in Geneva, Switzerland.
The researchers add that the risk associated with the presence of DCIS remained constant over the follow-up period, “emphasizing the importance of long-term follow-up”, for at least 20 years.
By contrast, women with high-grade invasive tumours had an elevated recurrence risk during the initial 5 years, after which the risk declined. Such patients should be “monitored closely”, especially early on, the study authors write in JAMA Oncology.
They also evaluated the effect of the boost radiation on recurrence in high-risk patients. For instance, among those aged less than 50 years with DCIS, receipt of a tumour bed boost versus no boost was associated with a significant 63% reduction in the risk of ipsilateral recurrence.
And the cumulative incidence of recurrence at 20 years was 15% for high-risk women who received boost radiation compared with 31% for those who did not, equating to an absolute decrease of 16%.
Noting that much has changed in breast cancer treatment since the trial was designed, the authors of a linked editorial question how best to incorporate these latest findings into clinical practice.
They observe that “certain women clearly remain at high risk” of recurrence following breast-conserving surgery, and these women – for instance, those younger than 50 years and with high-grade tumours – “should receive a boost after whole-breast radiotherapy”.
Laurie Cuttino (Virginia Commonwealth University, Richmond, USA) and Charlotte Dai Kubicky (Oregon Health & Science University, Portland, USA) conclude: “In the future, the use of molecular subtyping, radiosensitivity signatures, and other advances will likely provide more insight into which patients require radiotherapy after breast-conserving surgery, and who will benefit from higher doses to the tumor bed.”
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