The recurrence pattern following delayed breast reconstruction after mastectomy for breast cancer suggests a systemic effect of surgery on occult dormant micrometastases

The purpose of this study was to characterize the recurrence dynamics in breast cancer patients after delayed reconstruction. We hypothesized that surgical reconstruction might stimulate dormant micrometastases and reduce time to recurrence. All mastectomy breast cancer patients with delayed surgical reconstruction at Haukeland University Hospital, between 1977 and 2007, n = 312, were studied. Our control group consisted of 1341 breast cancer patients without reconstruction. For each case, all patients in the control group with identical T and N stages and age ±2 years were considered. A paired control was randomly selected from this group. 10 years after primary surgery, 39 of the cases had relapsed, compared to 52 of the matched controls. The reconstructed group was analyzed for relapse dynamics after mastectomy; the first peak in relapses was similarly timed, but smaller than for the controls, while the second peak was similar in time and size. Second, the relapse pattern was analyzed with reconstruction as the starting point. A peak in recurrences was found after 18 months, and a lower peak at the 5th–6th year. The height of the peak correlated with the extent of surgery and initial T and N stages. Timing of the peak was not affected, neither was the cumulative effect. The relapse pattern, when time origin is placed both at mastectomy and at reconstruction, is bimodal with a peak position at the same time points, at 2 years and at 5–6 years. The timing of the transition from dormant micrometastases into clinically detectable macrometastases might be explained by an enhancing effect of surgery.