Introduction: Breast reduction surgery is one of the most frequently performed surgeries amongst plastic and reconstructive surgeons worldwide. Previous studies have shown decreased risk of breast cancer development in women undergoing breast reduction surgery of up to 28%. We aimed to evaluate the relative risk of breast cancer development in our patients after breast reduction surgery in relation to the general female population of Austria. Methods: A total of 637 women underwent breast reduction surgery between 2003 and 2017 at our department. From those women, 513 patients completed a follow-up assessment of breast cancer development and were included into the study sample. The age-specific incidence rate data of the general female population of Austria served as the control group and basis for the calculation of the standardized incidence ratio (SIR) and Poisson test. Results: Relative to 5.66 expected cases of breast cancer, our cohort showed 1 subject with breast cancer after breast reduction surgery (SIR = 0.1765). An exact Poisson test was carried out to determine the level of significance of the difference between the incidence rate observed in the sample compared to the expected rate based on the age-specific incidence rates of the general population (p = 0.023, α = 0.05). Discussion: Our study underlines the strong evidence of previous studies for significant breast cancer reduction in patients after reductive mammoplasty. In comparison to the general female population of Austria, our cohort showed a reduction in breast cancer incidence of about 82%. The authors believe that different techniques in reduction mammoplasty have different levels of safety regarding the prevention and risk reduction for breast cancer. Further investigation must be conducted to evaluate the reduction of breast cancer risk with different surgical techniques.

Awareness and recognition of mamma hypertrophy as a morbid condition has greatly increased in recent years. This may partly be caused by increased patient awareness and information, improved medical care, or an established algorithm for health insurance coverage [1]. In Austria a mamma reduction is covered by insurance if the woman is not morbidly obese (ideally a BMI ≤27) and 500 g of breast tissue can be expected to be reduced on either side.

Breast reduction surgery is one of the most frequently performed surgeries among plastic and reconstructive surgeons worldwide. There are several techniques available for different breast sizes and configurations, all of which aim for eliminating symptoms like cervical syndrome, excessive sweating with eczema in the sub-mammary fold, or discomfort. Depending on the amount of breast tissue removed, as well as the physiological condition and habits (such as smoking) of the patient, complications may occur. These complications may include wound healing disorders, infections, or fat necrosis. The question arises of whether the risk of future carcinoma development is decreased by the removal of a certain percentage of breast parenchyma, or even increased, due to inflammatory processes and tissue scarring effects. Several studies from Sweden and Denmark have shown a decreased risk of breast cancer development in women undergoing breast reduction surgery of up to 28%, especially in women who had a significant amount of breast tissue removed [2-4]. In the past some authors have even suggested breast reduction surgery as an alternative to mastectomy in genetical or familial high- or medium-risk patients. However, this procedure is no longer up to date with current oncological standards [5].

The main objective of this study was to evaluate whether breast cancer risk may be de- or increased by previous reductive mammoplasty, with prior evidence suggesting a decreased risk. As breast cancer rates, screening, and therapeutic algorithms in Sweden and Denmark may differ from Austrian standards, we aimed to evaluate the relative risk for breast cancer development in our patients after breast reduction surgery in relation to the general female population of Austria.

Participants

Surgical records of 637 women who underwent breast reduction surgery at the Klinik Landstrasse (formerly Krankenanstalt Rudolfstiftung) hospital in Vienna between 2003 and 2017 were obtained from the department for plastic and reconstructive surgery. Each surgical record was included in the data set, including age at the date of surgery, weight, height, histological result of the removed breast parenchyma, smoking anamnesis, record of childbirth, as well as self-reported follow-up status for breast cancer incidence.

Follow-up assessment was conducted by phone interview between April and May in 2019. Each patient was called and asked about any occurrence of malignant tumors (including DCIS) of the breast.

Overall, 3 women were excluded from this study due to postoperatively diagnosed breast cancer through histological tissue examination, past breast cancer diagnosis, or revision breast reduction surgery, in order to eliminate bias and focus on primary mamma carcinomas after breast reduction surgery. Furthermore, we had to exclude 121 patients from the study due to loss of follow-up. We were able to include 513 women with at least 1 full year of follow-up into the data analysis.

Surgical Techniques

Most of the surgical techniques included Hall-Findlay (superio-medial pedicle) and Eren (central pedicle). Unfortunately, the specific surgical procedure could not be extracted from all surgical reports due to improper or lacking documentation, and was therefore not statistically evaluated.

Data Analysis

As for the calculation of person-years of observation in 5-year age groups, only the age at surgery and full years of follow-up since surgery were available; therefore, the person-years contributing to the study had to be approximated. Approximation was done by accounting 0.5 person-years for each entry and exit year and 1 person-year for each year in between. We then attributed the person-years for each subject to the appropriate 5-year age group and added up those values to get the sample values.

Since our sample is not large enough to directly calculate an age-standardized incidence rate reliably, indirect age-standardization was applied. Age-specific incidence rates for the female population of Austria from 2003 to 2017 were obtained from Statistik Austria, Bundesanstalt Statistik Österreich, Österreichisches Krebsregister (stand December 09, 2019) and Todesursachenstatistik for the calculation of expected cases and standardized incidence ratios (SIR) [6]. Due to the relatively small data set, further age-specific analysis was not performed because of possible distortion bias.

In addition, a one-sided exact Poisson test was performed to determine the level of significance of the established differences in observed versus expected breast cancer incidence rates, with the hypothesis that the observed incidence rate is lower than the expected incidence rate when the age-specific incidence rates of the general female population of Austria are applied. Statistical analysis was carried out using R programming language [7-10].

In total, 513 subjects with a median age of 41.5 years (range 17.5–77.5) at the time of breast reduction surgery could be included in the analysis. Figure 1 provides the absolute frequencies of our sample regarding the age groups at surgery. Overall, 4,546 person-years were contributed to the sample with a mean follow-up length of 8.86 years and a range from 1 to 16. The crude rate found in the sample was 22 per 100,000 person-years (95% CI 0.6–122.6).

Fig. 1.

Patient count by age group (years) at the time of surgery.

Fig. 1.

Patient count by age group (years) at the time of surgery.

Close modal

Relative to 5.66 expected cases of breast cancer (including DCIS) if the age-specific incidence rates of the general female population were applicable, our cohort showed 1 subject with breast cancer after breast reduction surgery (SIR = 0.1765; 95% CI 0.0045–0.9833). The upper border of the confidence interval not reaching 1 already indicated the difference in incidence rates between our study cohort and the control group. Table 1 shows the observed versus expected breast cancer cases, as well as person-years by age group and age-specific incidence rates in the sample and Austrian female population of 2017.

Table 1.

Observed versus expected breast cancer cases

Observed versus expected breast cancer cases
Observed versus expected breast cancer cases

An additional Poisson test was carried out to determine the level of significance of the difference between the observed incidence rate in the sample and the expected rate based on the age-specific rates in the general population and the person-years in our sample. The Poisson test was significant at p = 0.023 (α = 0.05).

Our study supports the strong evidence of previous studies for significant breast cancer reduction in patients after reductive mammoplasty [4]. In comparison to the general Austrian female population, which has a reported age-standardized incidence rate of 113.3 per 100,000 person-years, our cohort showed a reduction in breast cancer incidence of about 82% (based on the SIR) [6].

Regarding risk factors for cancer development, 27.8% of our patients showed a record of smoking versus 22.1% in the general female Austrian population in 2014 (data set provided by Statistics Austria) [11]. Despite our cohort showing slightly more nicotine use, the breast cancer incidence rate in our sample was clearly reduced by 82%. A certain bias may be possible due to the recommendation for nicotine abstinence before and after breast surgery in our clinic for an improvement in wound healing, fat necrosis, and infection rate. However, a certain retrospective evaluation of smoker incidence is not possible since patients might not have followed recommendations due to incompliance. This must be taken into consideration since previous studies have shown a significant higher risk for developing breast cancer in patients with nicotine abuse [12, 13]. Additionally, our patients apparently showed a slightly higher average BMI (mean = 25.83, SD = 3.13) than the average female population in Austria (mean = 24.4), which could have further increased the risk of breast cancer formation [14].

Brinton et al. [3] showed a clear correlation between the resection weight of breast parenchyma and amount of risk reduction and undermined the hypothesis of increased malignant tendencies due to larger glandular mass. This was especially evident in patients who had a reduction of ≥800 g per side. For these women a cancer reduction of 76% could be achieved even compared to women with a reduction of <400 g. Unfortunately, in our study the average resection weight could not be analyzed due to lacking information regarding the histological documentation.

The authors believe that different techniques in reduction mammoplasty have different levels of safety regarding the prevention and risk reduction for breast cancer. As most breast cancers occur in the upper outer quadrant, pedicles sparing this sector may be less safe. Following this theory, lateral pedicles would be considered least safe [15]. Procedures like free nipple graft mammaplasty, despite being decreasingly used due to inferior aesthetical outcomes, could be the safest method as the largest percentage of breast tissue is removed during surgery. Further investigation must be done to evaluate the reduction in breast cancer risk in different surgical techniques.

As with reduction mammoplasty not all breast parenchyma is removed, the chances of breast cancer development cannot be non-existent. Theoretically, the relative risk per centimeter squared of remaining tissue is even increased compared to pre-operative conditions, as scarring or slight inflammation, both as normal postoperative processes, could lead to DNA damage and consequently to elevated breast cancer risk. Additionally, it is important to notice, that a reduction mammoplasty certainly leaves behind more breast tissue than a regular mastectomy and can therefore never be as safe in preventing future breast cancer.

Our cohort size is rather small in comparison to other studies mentioned in this article because there is no complete data set in respect of the development of breast cancer after breast reduction surgery for all Austrian clinics available [4]. Therefore, a follow-up study is planned to possibly include further hospitals as well as to expand the patient data set for a longer time period. More data are also needed to further investigate age-specific differences in the development of breast cancer after breast reduction surgery and to be able to examine differences in the occurrence of breast cancers of for example 5-, 10-, and 15-year periods after breast reduction surgery was performed.

Possible bias may have been introduced to our survey via the telephone interviews. Some patients could not be included because of an inability to contact them, as well as unwillingness to give out information about their current medical condition or history. Also, some of our patients who are not included in the analyzed sample may have developed and/or passed away from breast cancer and might therefore have been unable to be contacted.

Overall, our study supports the current opinion of breast reduction surgery lowering the lifetime risk of breast cancer formation. Evaluation of risk reduction with different surgical techniques used should be performed in future studies.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards; EK-18-255-VK, Ethics Committee of Vienna (Ethikkommission der Stadt Wien). Informed written consent was obtained from all individual participants included in the study.

All named authors hereby declare that they have no conflicts of interest to disclose.

All named authors hereby declare that they have no conflicts of interest to disclose. No funds were received for this study.

Al.N.: main author. S.S., Ar.N., V.K., F.S., D.H., R.K.: co-authors. M.Z., C.S., S.P.: co-investigators. L.S.: supervisor, main investigator.

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