The early detection of ILRR and CBC plays a major role for morbidity and mortality of BC survivors (Dunst et al. 2001). The knowledge about risks is highly imported in counseling patients. There is evidence about the increased risk for CBC for BRCA1 or 2 mutation carriers depending on their age at primary diagnosis and the time since primary diagnosis (Kuchenbaecker et al. 2017). Thus, HBOC BC survivors can already take their CBC risks into account when planning primary surgery including prophylactic procedures of the contralateral breast or remain in an intensified imaging program.

While diagnostic modalities have improved significantly over time and there are lots of new potent-targeted therapies available, one should scrutinize our restrained approach of the aftercare management of all BC patients that is based on the motto “one fits all”. Even though we already have evidence that MRI is improving detection rates, we still perform mammography and ultrasound screening only in the aftercare of BC in case of the absence of HBOC history (Eisen et al. 2024).The use of breast MRI is generally restricted to specific situations such as HBOC history or CUP (cancer of unknown primary) syndrome. Moreover, starting in 2001, national health insurances recognize the use of MRI as helpful for the diagnosis of ILRR after breast-conserving therapy or after mastectomy with reconstruction of the breast using implants. Since then, they financially support breast MRI in case of uncertain findings of mammography and ultrasound in patients with BC history (G-BA 2001). However, a routine MRI for the detection of ILRR or CBC is still not considered the standard of care.

Since, the majority of literature concerning ILRR/CBC detection is several decades old, we further analyzed latest data in our breast cancer center over a 5-year period of time. In our institution, we found a rate for ILRR or CBC of 12.6% which is congruent with the literature (Pan et al. 2017; Xiong 2018). Of those patients, 23.8% had a history of HBOC, which also reflects common knowledge.

Detection of ILRR and CBC in rT1 stages was achieved in 73% of all patients. It is known that outcome depends on early detection, since there is scientific evidence that tumor size is a risk factor for another ILRR (re-recurrence) (Wapnir et al. 2006). Furthermore, we were able to show that those patients that did not receive MRI were more often diagnosed with higher tumor size (T stage). In most cases, BC of NST was diagnosed, which is known to be the most common histological subtype (Strehl et al. 2011). But we also found that invasive lobular BC was mainly detected in nHBOC patients (14.1%), while HBOC patients were diagnosed with invasive lobular BC in only 2.2%. Of note, while CDH1 mutations are associated with invasive lobular carcinoma, those mutations are found in less than 1% of all BC patients (Euhus 2014). In contrast, BRCA1 germline pathogenic variants are not associated with an invasive lobular subtype (Yadav et al. 2021). Based on our analyses, we also found that HBOC patients more often showed aggressive tumor subtypes with Ki67 > 25%.

Higher breast density was associated with younger age and led to decreased detection of ILRR and CBC in mammography (Yeom et al. 2019). The percentage of patients with ILRR and CBC was equally high in HBOC patients and patients without a history of HBOC. This fact is interesting since one would expect a higher rate of CBC in patients with HBOC. It has been shown previously that especially those HBOC patients with pathogenic mutations for BRCA1 and 2 have an increased risk for CBC depending on the age at initial diagnosis (Kuchenbaecker et al. 2017). One reason might be the low amount of patientis in this group. Another reason that there is still a relevant amount of patients with familial cancer history suggestive of HBOC who have not been counseled or tested for pathogenic mutations. But since, we discuss risk-reducing surgery on the contralateral breast for those patients with pathogenic variants of BRCA1/2 based on the risk of about 30% to develop CBC, the presented data is of crucial importance.

HBOC patients who received an intensified-aftercare program showed more often ILRR with the same histological subtype, while those patients without a history of HBOC more often showed a divergent histological subtype for ILRR. There is no literature available about this fact. We assume that the reason lies within the tumorigenic potential/behavior of the breast tissue in HBOC patients, while there might have been multifocal or multicentric primary disease with undetected divergent histopathology in nHBOC patients or ILRR might be based on incomplete primary resection status. It is known that pathogenic variants of BRCA1 are associated with triple-negative subtypes and those of BRCA2 with hormone receptor positive subtypes (Engel et al. 2020).

We detected the highest sensitivity for the detection of ILRR or CBC using MRI. Lee et al. analyzed the use of MRI in the aftercare of BC patients after breast-conserving therapy. They found that detectability for recurrent disease was significantly higher using MRI (99%) in comparison to mammography (59.4%) and ultrasound (68.9%). They further identified early fast enhancement as a major feature to detect recurrent disease after surgery of the breast (Lee et al. 2021). These data are in line with our findings and underline the importance of MRI.

CBC after risk-reducing surgical treatments in HBOC patients needs to be further investigated. There are publications showing CBC rates of up to 11% despite of bilateral mastectomy (Allue Cabanuz et al. 2020). On the contrary, Van Sprundel et al. showed a significantly reduced risk for CBC after risk-reducing surgery (1.3% vs. 46.4%) and a 5-year OS of 94% vs. 77% for BRCA1/2 mutation carrier (van Sprundel et al. 2005). Influencing factors might be the applied surgical technique and thus the amount of removed breast tissue. Breast MRI might help to identify postoperative remaining breast tissue. But there is still no evidence about assessment criteria of relevant remaining tissue in MRI.

Evidence for HBOC patients with moderate penetrance gene mutations is even less available. Also taken into consideration are analyses on patient reported outcomes. There are statements that the fear of cancer recurrence was higher in patientin with contralateral risk-reducing procedures (Srethbhakdi et al. 2020).

There are several attempts to improve and individualize the aftercare of patients with BC according of their risks and needs. One of those is the follow up program called BETTER-CARE (“BrEasT cancer aftTERCARE follow up and program “), a German study that investigates a multidisciplinary approach to improve patients’ quality of life. Funded by the German federation, it also comprises digital solutions for improved networking of all professionals involved in the aftercare of a patient (Wöckel and Heuschmann 2024).

Limitations of this study are the retrospective design and a relatively low amount of patients included in the analysis. There are several aspects, e.g., economical, false-positive and false-negative results of an imaging modality, as well as side effects that could not be assessed due to the study design but that play major role in identifying an optimized aftercare. In search of an optimized aftercare, one should also take into account that the majority of literature available is old and reflects times before individualized therapy concepts became the standard of care.