Breast-conserving surgery and RT constitute the preferred local treatment of early BC. RAASB is a serious but fortunately uncommon complication of RT. The current study assessed RAASB treatment and prognosis in a nationwide population. We found that a radical surgical operation with curative intent is possible in the majority of RAASB patients. The 5- and 10-year OS rates of 69% and 52%, respectively, compare favorably with previous studies, mostly institutional series, reporting 5-year OS rates of 10–75%,8,10,12,20 and a recent large (n = 209) nationwide study reporting 5- and 10-year OS rates of 41% and 25%, respectively.6 The large variation in survival is presumably derived from the diverse patient populations.
The primary treatment of localized RAASB is surgery. Awareness and early diagnosis of RAASB is crucial to enable surgical treatment with curative intent. In the present study, almost all patients (94%) underwent surgery for RAASB. The type of surgery, amount of removed tissues, and methods of surgical reconstruction varied considerably, reflecting the nationwide patient population and variable policies of treating hospitals. Previous research has emphasized the importance of extensive radical operations to improve survival.11,13 In a study of 38 RAASB patients, 36 (95%) patients were operated on with curative intent,13 of whom 23 had a radical excision with surgical reconstruction and 13 had a non-radical excision. The authors observed a greater number of local recurrences in patients with < 1 cm margins, and concluded that at their institution, RAASB management currently involves a radical excision of the irradiated breast area. In a retrospective analysis from a tertiary center, a simple mastectomy alone was performed in 4 of 13 surgically treated patients.8 In the current study, the practice of removing the irradiated breast area was not followed. Instead, the surgical treatment consisted of a radical excision of the lesion with a median planned surgical side margin of 4.0 cm. The removal of all the irradiated breast area may require extensive and mutilating surgical operations and surgical reconstruction. One study has suggested that radiation-associated sarcomas arise in or at the edge of the radiation field.21 This view was further supported by a recent study that proposed that RAASB “arise from a field change within the irradiated tissue”.13 In the current study, the tissue defect was most often covered with pedicled latissimus dorsi flaps; however, detecting an RAASB recurrence can be more difficult if a pedicled flap is used. On the other hand, skin grafts may allow for a more reliable follow-up of the affected area.
We found that a larger planned surgical side margin was prognostic for OS, and there was also a non-significant trend towards an improved OS for the margin measured in the pathologist’s report. The weaker association with the pathologist’s assessment of the margin may reflect the difficulty in determining the extent of RAASB due to the multifocal growth pattern of RAASB, as previously postulated.11 While surgical margins were not statistically significantly associated with local or distant recurrences, they showed weaker trends towards a better outcome, with wide CIs. Some previous studies have not found any association between the surgical margin and a local recurrence9,14 or OS.20,22 On the other hand, a study including both primary and secondary angiosarcomas of the breast reported an improved OS for patients with negative surgical margins.23 Moreover, one study defining radical margins as removal of all or nearly all previous irradiated breast skin reported an improved 5-year disease-specific survival of 86%, versus 46% for radically versus conservatively operated patients.11 It is important to note that most individual studies, including the present study, are small, making assessment of prognostic factors unreliable. Due to its retrospective nature, the current study is missing information regarding the planned surgical side margin and pathological surgical side margin in a number of patients. It is important to bear in mind the possible bias in these results. A meta-analysis of published data comprising 222 RAASB patients reported that tumor size (p < 0.0005) and combination treatment with surgery and irradiation (p = 0.01) improved local control significantly, while tumor size (p < 0.0005), and age (p = 0.048), were prognostic for OS.24 Surgical margins were not assessed in this meta-analysis.
A notable finding in the current study was the high risk of local RAASB recurrence (45%). Ninety percent of these patients underwent salvage surgery, and, at last follow-up, only 6 of 21 (29%) patients remain alive without further recurrences. Previous investigations of RAASB have reported local recurrence rates ranging from 30 to 92% of patients.8,9,12,13,–14,17 Unfortunately, only a few of these studies provide further follow-up data after local recurrence. In a study of 79 RAASB patients, only 25% of patients with a local recurrence later succumbed to RAASB.14 Therefore, the authors suggested an intensive treatment of local recurrences to improve survival. In another study, a local recurrence was found in 19 of 31 (61%) patients,22 of whom 11 had a surgical excision of the recurrence, with a median survival of 34 months compared with 6 months in patients with no surgical intervention. Our results corroborate the previous findings and further support a radical surgical approach with curative intent in a local recurrence. In our institution, the follow-up plan also includes photographs of the affected area. The initial follow-up interval is short, with gradual prolongation if no recurrences occur.
In the current study, only one patient received postoperative RT and five patients received postoperative chemotherapy. In previous studies, the use of pre- or postoperative chemotherapy has ranged from 3% to 45% and no firm conclusions can be drawn regarding its beneficial impact.11,12,14,17,20,22 Administration of RT for RAASB is controversial due to the previously delivered RT for BC and the presumably RT-induced etiology of RAASB. In the literature, the application of pre- or postoperative RT has ranged substantially from 4 to 35%.10,12,20,25 Whether RT was administered pre- or postoperatively is often not declared. One study reported an improved disease-free survival at 2 years after adjuvant RT (explicit information on RT schedule was not disclosed), however both primary breast angiosarcoma and RAASB were included and the study population was small (n = 35).25 In another population-based study of exclusively RAASB, no survival advantage was reported for patients managed with both surgery and RT compared with surgery alone.6
The results of our report are subject to at least three limitations. First, this was a retrospective study and it is possible that reporting to the nationwide cancer registry has been incomplete. However, this is unlikely because the FCR has an estimated coverage of 96% in all solid tumors and 82.9% in tumors of bone and soft tissues.26 Second, treatment policies may have changed during the study period. However, the year of RAASB diagnosis did not affect prognosis. Third, although relatively large, our patient population is underpowered to detect prognostic factors with a small or moderate impact. The most important strengths originate from the population-based patient cohort, systematic confirmation of RAASB from hospital and pathology records, and complete follow-up of all patients. RAASB treatment in Finland is mainly concentrated in the five university hospitals; however, some patients are treated in local hospitals. It is therefore possible that RAASB treatment protocols may differ and this may influence the results observed in this research.