Abstract
Background/Aim: If ductal carcinoma in situ (DCIS) is diagnosed by needle biopsy, invasion is often found by removing the entire tumor and performing pathological examination. Smoking is a risk factor for carcinogenesis in breast cancer. We examined the correlation between the risk of invasion found by postoperative pathology and smoking history in patients diagnosed with DCIS by preoperative biopsy. Patients and Methods: We examined 128 patients who were diagnosed with DCIS by preoperative biopsy. Multivariate analysis was performed on the risk factors for invasion diagnosed by postoperative pathological examination in all cases diagnosed with DCIS by preoperative biopsy. Results: Multivariate analysis was performed on the risk factors for invasion diagnosed by postoperative pathological examination in all cases diagnosed with DCIS by preoperative biopsy. Number of pack-years was not an independent factor (p=0.349, OR=0.329), but current-smoker status (p=0.006, OR=not calculable) was an independent factor with VAB (p=0.018, OR=0.327). Conclusion: Tobacco components may have an influence on the progression from DCIS to invasive ductal carcinoma.
If ductal carcinoma in situ (DCIS) is diagnosed by histological examination such as core needle biopsy (CNB) or vacuum-assisted biopsy (VAB), invasion is often found by removing the entire tumor and performing pathological examination. According to a meta-analysis, the ratio of invasive ductal carcinoma (IDC) found by postoperative pathological examination is 25.9% (18.6-37.2%) (1). Various underestimated risk factors for invasion have been reported, including the grade of DCIS (1). The natural history of the progression from DCIS to IDC is unknown (2, 3). However, it is generally believed that the carcinogenesis process for breast cancer progresses from normal breast tissue to atypical ductal hyperplasia, then to DCIS, and lastly to invasive breast cancer (4-6).
Smoking is a risk factor for carcinogenesis in various carcinomas and breast cancer is no exception (7). Several studies, in vivo and in vitro, have shown that tobacco smoke components increase breast cancer cell proliferation and cause malignant transformation (8-10). In reports investigating whether smoking is a risk factor for DCIS, no correlation was found in a large-scale cohort or case-control studies, while another case-control study showed an inverse correlation between smoking and DCIS (11-13).
There has been no report of smoking as a risk factor to underestimate DCIS by biopsy. However, there are reports about tobacco components reaching the mammary gland tissue through the blood, causing DNA damage (14, 15). We hypothesized that DCIS may also be affected by smoking components, causing increased malignancy. Based on this hypothesis, we examined the correlation between the risk of invasion found by postoperative pathology and smoking history in patients who were diagnosed with DCIS by preoperative biopsy.
Patients and Methods
Patients’ background. In this study, we examined 128 patients who were diagnosed with DCIS by preoperative biopsy from August 2007 to January 2018 at the Osaka City University Hospital. Before the biopsy, all patients were asked about the duration of smoking, the number of cigarettes smoked per day, and whether they were currently smoking. Based on their smoking status, the patients were classified as never-smokers, current-smokers, and former-smokers. The total number of smokers was the sum of current-smokers and former-smokers. The data were used to calculate each patient’s tobacco exposure based on pack-years (16). Then, all patients were diagnosed with DCIS pathologically by CNB or VAB. The biopsy tissue was used to assess the grade of DCIS based on the World Health Organization classification (17), comedo necrosis, intraluminal calcification, and interstitial inflammation [as previously reported (18, 19)]. Immunohistochemical staining was performed in the biopsy tissue to evaluate the expression of the estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), and Ki67 in cancer cells. Tumor size was measured by ultrasonography, computed tomography (CT), and magnetic resonance imaging. Cases suspected of invasion or metastasis by these imaging techniques were excluded. About half of all patients did not undergo mammography. All patients underwent mastectomy or breast-conserving surgery after being diagnosed with DCIS.
Statistical analysis. The JMP software package version 15 (SAS, Tokyo, Japan) was used for all statistical analyses. The relationship between each factor was examined by the Pearson’s chi-square test. Logistic analysis was used for calculating the odds ratio (OR) and 95% confidence interval. The multivariate logistic regression model was used for multivariate analysis. A p-value lower than 0.05 was defined as significant.
Ethics statement. This study was conducted at the Osaka City University Graduate School of Medicine (Osaka, Japan). The study protocol involved a retrospectively written research, pathological evaluation, and statistical analysis plan. The study complied with the provisions of the Declaration of Helsinki, and all patients provided written informed consent for their treatment and data collection. The study’s retrospective protocol was approved by the ethics committee of Osaka City University (approval number #926).
Results
Clinicopathological features. The clinicopathological features of 128 patients diagnosed with DCIS by preoperative biopsy are listed in Table I. The median age was 51 years (range=30-78 years), and 17 patients (13.2%) were under 40 years old. Eighty-three patients (64.8%) had some symptoms, and the tumor was palpable at medical consultation in ninety-three patients (72.7%). Forty-five patients (35.2%) were asymptomatic and were found by routine screening for breast cancer or CT examination for other diseases. The median tumor diameter was 17.7 mm (range=3.0-50.0 mm). For the biopsy method, 73 patients (57.0%) were diagnosed by CNB, which was more than that by VAB. The expression of ER and PgR were positive in 104 (81.3%) and 87 (68.0%) DCIS cases, respectively. Regarding HER2, the score was 2+ in 22 patients (17.2%) and 3+ in 19 patients (14.8%). The expression of Ki67 was higher than 14% in 27 patients (21.1%). Regarding the grade of DCIS, 53 patients (41.4%) had low-grade, 51 (39.8%) had intermediate-grade, and 24 (18.8%) had high-grade DCIS. In the biopsy specimens, comedo necrosis was found in 68 patients (53.1%), and intraductal calcification was found in 21 patients (16.4%). Lymphoid infiltrate was classified into four stages: Stage1, Stage2, Stage3, and Stage4; it was evaluated as moderate or severe in 39 patients (30.4%). IDC was found by postoperative pathological examination in 50 patients (39.1%).
Clinicopathological features of 128 cases diagnosed with DCIS by preoperative biopsy.
Regarding smoking, the majority of patients were never-smokers (107 patients, 83.5%). Eight patients (6.3%) smoked at diagnosis of DCIS (current-smokers), and thirteen patients (10.2%) had quit smoking before diagnosis (former-smokers). Twelve patients (9.4%) smoked more than ten cigarettes per day, which were more than half of the total number of smokers. Regarding the period of smoking, 7 patients (5.5%) smoked for 10 years or less, 9 patients (7.0%) smoked for 11 to 20 years, and 5 patients (3.9 %) smoked for more than 20 years. Tobacco exposure was 10 or less pack-years for 11 patients (8.6%) and more than 10 pack-years for 10 patients (7.8%).
Risk factors for finding invasion in postoperative pathological examination (univariate analysis). Univariate analysis was performed on clinicopathologic features in which invasion was found in postoperative pathology, and the results are shown in Table II. IDC tended to be found postoperatively in patients who had symptoms at diagnosis (p=0.082, OR=1.980) or whose tumor was palpable (p=0.058, OR=2.278). The OR and tumor size were positively correlated, and tumors larger than 30 mm were significantly more invasive than those smaller than 10 mm (p=0.015, OR=4.518). DCIS diagnosed by VAB was significantly more invasive than DCIS diagnosed by CNB (p=0.018, OR=0.407). Invasion was found more frequently in postoperative pathology in ER negative DCIS than in ER positive DCIS (p=0.009, OR=0.304). The relation with PgR was similar but not significant (p=0.053, OR=0.476). Regarding HER2, patients with a score of 3 were more likely to have invasion than did patients with scores of 0 or 1 (p=0.027, OR=3.097). In cases with DCIS with high Ki67 there was a significantly higher risk of finding IDC than in DCIS with low Ki67 (p=0.016, OR=0.304). Furthermore, high-grade DCIS was significantly more likely to have IDC in postoperative pathological diagnosis than did low-grade DCIS (p=0.007, OR=3.889). With respect to lymphoid infiltrate, the risk of finding invasion increased as the density of lymphocytes surrounding DCIS increased. As a result, compared with negative-lymphoid infiltrate, invasion was found to be significant in DCIS that had moderate (p=0.004, OR=4.606) or severe (p=0.029, OR=5.333) infiltrates.
Univariate analysis of postoperative pathology.
Regarding smoking, no significant difference was found between never-smokers and smokers. However, no current-smokers were found to have IDC by postoperative pathological examination, which was significantly different from never-smokers (p=0.021, OR=cannot be calculated). As the number of cigarettes smoked per day and the smoking period increased, the OR decreased, but it was not significant. When examined by pack-years, IDC was rarely found in patients with more than 10 pack-years of tobacco exposure compared to never-smokers (p=0.053, OR=0.159).
Correlations between clinicopathological features and smoking status. The correlations between smoking status and clinicopathological features showed that the number of smokers was significantly higher in younger patients (under 40 years old) than in middle-aged or older patients (over 40 years old) (p<0.001) (Table III). Former-smokers and current-smokers were significantly younger than never-smokers (p=0.008, p<0.001 respectively). Current-smokers presented with significantly more symptoms than did never-smokers (p=0.029). However, no other clinicopathological features differed based on smoking status. There was no correlation with any clinicopathological features when divided into two groups with a cutoff value of 10 pack-years. Comparing former-smokers and current-smokers, former-smokers smoked significantly fewer cigarettes per day (p=0.027) and had a significantly higher rate of invasion in postoperative pathology (p=0.023) (Table IV).
Correlation between smoking status and clinicopathological features (smoker, smoking status, pack-years).
Correlation between smoking status and clinicopathological features (not current smokers, current smokers, former smokers).
Risk factors for finding invasion in postoperative pathological examination (multivariate analysis). Multivariate analysis was performed on the risk factors for invasion diagnosed by postoperative pathological examination in all cases diagnosed with DCIS by preoperative biopsy (Table V). Number of pack-years was not an independent factor (p=0.349, OR=0.329), but current-smoker status (p=0.006, OR=not calculable) was an independent factor with VAB (p=0.018, OR=0.327).
Univariate and multivariate analysis of upstaging preoperatively DCIS to invasive cancer.
Discussion
There are various reports about risk factors for finding IDC by postoperative pathological examination in cases diagnosed as DCIS by preoperative biopsy. A meta-analysis lists the following items as risk factors: biopsy devices, high-grade DCIS, tumor larger than 20 mm, palpability, and others (1). There are also reports that list negative hormonal receptor (20, 21), HER2 over-expression (22, 23), and lymphoid infiltrate as risk factors (18, 19). However, other reports do not identify these clinicopathologic features as risk factors (24). No study reporting high Ki67 as a risk factor was found, but it was thought that DCIS with HER2 over-expression or high Ki67 had a potential risk of invasion because these features represented a high risk for postoperative DCIS recurrence (25-27).
In this study, the same clinicopathological factors as those previously reported were identified as risk factors for finding infiltration after surgery. However, the patients included in this study differed from the patients of previous reports in terms of clinicopathologic features. An important difference is the rate of IDC found by postoperative pathological examination. In the meta-analysis previously reported, the ratio was 25.9% (18.6-37.2%) (1), while we found a higher rate of 39.1%. We presume that this difference is due to the biopsy device. We have been using 16-gauge CNB because of the physical burden on patients. As a result, IDC was found by postoperative pathological examination at a high-rate of 47.9% in cases diagnosed by CNB, which may have affected the overall rate of IDC found by postoperative pathological examination.
Another difference is that fewer patients had the clinicopathological features listed as risk factors. For example, the palpable tumor rate was 8.8-fold higher in this study compared with a previous report (1). Similarly, the over-expression rate of HER2 was 14.8% in this study and 28-65% in a previous report (28). In addition, high-grade DCIS corresponded to 49.4% of cases in a previous report (1) but only 18.8% in this study. These differences may exist due to the low rate of breast cancer screening in Japan, which is lower than that in other countries at 40% (29). The fact that various risk factors are lower than those reported previously may indicate that, in many cases, invasion already occurred at the time the patient presented to the hospital.
In this study, postoperative IDC was less frequently found in current-smokers compared to never-smokers and former-smokers. In addition, the risk of finding IDC decreased with increasing daily smoking and smoking duration, although these were not significant. This is supported by the results of a case-control study (13). In that study, the current status as a smoker was more important for the onset of DCIS than the exposure to tobacco, and the result was an inverse correlation (13). However, in vivo and in vitro experiments have shown that tobacco components increase the malignancy of breast cancer cells (8-10). In addition, we have shown in clinical samples that smoking can enhance HER2 expression in breast cancer and increase tumor-infiltrating lymphocyte density in the microenvironment surrounding the cancer (16, 30). From these results, we speculate that smoking may affect DCIS during the beginning of the disease, causing it to acquire invasive ability at an early stage and resulting in IDC identified by biopsy at initial diagnosis. Our speculation is supported by a case-control analysis that listed smoking as a risk factor of developing luminal A IDC, whereas it was associated with reduced risk of developing luminal A DCIS; however, the associations were not significant (31).
Some of the limitations of this study are the higher rate of postoperative IDC detection and the fewer number of patients with the risk factors previously reported. In addition, the data regarding smoking habits may not be entirely accurate because they were based on self-reporting. Because some studies listed younger age as a risk factor for finding invasion by postoperative pathological examination (32-34), the fact that the age distribution was disproportional between smoking and non-smoking patients may represent a small limitation.
Conclusion
This study suggests that tobacco usage may have an influence on the progression from DCIS to IDC, contributing to the elucidation of the underlying mechanism involved in this change.
Acknowledgements
The Authors thank Yayoi Matsukiyo and Tomomi Okawa (Department of Breast and Endocrine Surgery, Osaka City University Graduate School of Medicine) for the helpful advice regarding data management. This study was funded by grants from the Japan Society for the Promotion of Science (KAKENHI, Nos. 19K18067, 20K08938, and 17K10559) to Shinichiro Kashiwagi.
Footnotes
Authors’ Contributions
All Authors were involved in the preparation of this manuscript. KT collected the data and wrote the manuscript. SK, YA, WG, and TM performed the operation and designed the study. KT, SK, MS, and HT summarized the data and revised the manuscript. KH and MO provided a substantial contribution to the study design, performed the operation, and revised the manuscript. All Authors read and approved the final manuscript.
Conflicts of Interest
All of the Authors have no conflicts of interest to disclose regarding this study.
- Received October 30, 2021.
- Revision received November 19, 2021.
- Accepted November 22, 2021.
- Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
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