Neoadjuvant chemotherapy (NAC) has become a standard therapy for patients with advanced breast cancer. Pathological complete response (pCR) after NAC is an important prognostic indicator, but some patients with pCR continue to experience recurrence. So new predictive and prognostic markers in addition to pCR are needed following NAC for breast cancer. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can evaluate metastases in the entire body simultaneously, and has several potential advantages over conventional imaging modalities. The purpose of this study was to evaluate whether FDG-PET/CT can determine NAC response and whether FDG-PET/CT can be a new prognostic marker. We imaged 83 breast cancer tumors with FDG-PET/CT, ultrasound (US), and magnetic resonance imaging (MRI) to evaluate NAC efficacy. As we previously analyzed 110 breast cancers with FDG PET/CT, we defined a threshold of >1.7 maximum standardized uptake value (SUVmax) as abnormal fluorodeoxyglucose (FDG) uptake. After NAC, 16 (19.3 %) tumors had a complete response, 54 (65.1 %) had a partial response, 11 (13.3 %) showed stable disease, and 2 (2.4 %) showed progressive disease. One of the two patients with progressive disease had bone metastasis detected by FDG-PET/CT and was not operated on. Remote metastases were evident in 2.4 % of patients after NAC as determined by FDG-PET/CT. Overall, 17 patients had pathological complete response (pCR). The sensitivity of abnormal FDG uptake after NAC for non-pCR was 20.3 % and the specificity was 94.7 %. Patients with abnormal FDG uptake after NAC experienced significantly more recurrences (P = 0.004) and more of them died (P = 0.010). Moreover, the difference in disease-free survival was more significant in the estrogen receptor (ER)-negative group. FDG-PET after NAC may be more effective for predicting prognosis than for evaluating treatment response. This tendency was particularly remarkable in ER-negative breast cancer tumors. FDG-PET/CT is useful for reevaluating surgical applicability after NAC.

Preoperatively diagnosed ductal carcinoma in situ (DCIS) is sometimes upstaged to invasive cancer by postoperative pathological examination. Various preoperative factors associated with upstaging to invasive cancer have been reported; however, this subject remains to be clarified. DCIS takes various forms on imaging, but many cases show non-mass-type lesions. In non-mass-type DCIS, recognizing the presence of invasion is difficult. To investigate predictors associated with upstaging to invasive cancer more precisely, we examined only non-mass-type DCIS. The present study retrospectively analyzed 101 patients diagnosed with non-mass-type DCIS preoperatively on breast biopsy at our institution between 2007 and 2017. Data were analyzed using Fisher's exact probability test and two-sample t-tests. Multivariate analysis was performed using logistic regression. The results showed that 27 patients (27%) were finally diagnosed with invasive cancer. Univariate analysis revealed abnormal result of palpation on breast examination (P=0.05), comedo necrosis (P=0.05), and HER2 status (P=0.02) as significant predictors. Multivariate analysis revealed an abnormal result of palpation as an independent predictor of invasive cancer underestimation (odds ratio 4.76; confidence interval 1.44-15.7; P=0.01). In conclusion, preoperatively diagnosed non-mass-type DCIS represented an underestimation in approximately 27% of cases. In particular, the presence of a clinically abnormal palpation increases the chance of upstaging to invasive cancer.

This retrospective study examined the relationship between the standardized uptake value max (SUVmax) of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and the prognostic stage of breast cancer. We examined 358 breast cancers in 334 patients who underwent 18F-FDG PET/CT for initial staging between January 2016 and December 2019. We extracted data including SUVmax of 18F-FDG PET and pathological biomarkers, including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and nuclear grade. Anatomical and prognostic stages were determined per the American Joint Committee on Cancer (eighth edition). We examined whether there were statistical differences in SUVmax between each prognostic stage. The mean SUVmax values for clinical prognostic stages were as follow: stage 0, 2.2 ± 1.4; stage IA, 2.6 ± 2.1; stage IB, 4.2 ± 3.5; stage IIA, 5.2 ± 2.8; stage IIB, 7.7 ± 6.7; and stage III + IV, 7.0 ± 4.5. The SUVmax values for pathological prognostic stages were as follows: stage 0, 2.2 ± 1.4; stage IA, 2.8 ± 2.2; stage IB, 5.4 ± 3.6; stage IIA, 6.3 ± 3.1; stage IIB, 9.2 ± 7.5, and stage III + IV, 6.2 ± 5.2. There were significant differences in mean SUVmax between clinical prognostic stage 0 and ≥II (p < 0.001) and I and ≥II (p < 0.001). There were also significant differences in mean SUVmax between pathological prognostic stage 0 and ≥II (p < 0.001) and I and ≥II (p < 0.001). In conclusion, mean SUVmax increased with all stages up to prognostic stage IIB, and there were significant differences between several stages. The SUVmax of 18F-FDG PET/CT may contribute to prognostic stage stratification, particularly in early cases of breast cancers.

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Breast cancer metastasizes mainly to organs such as bone, lung, and liver, whereas metastases to the peritoneum and urinary tract are rare. Metastasis to the peritoneum or urinary tract may result in renal dysfunction, infection, and painful hydronephrosis. In our hospital, 1,409 breast cancer surgeries were performed between January 2004 and December 2015, and 7 cases of hydronephrosis associated with recurrence were observed. The median age of patients was 69 years (57–79 years). The median time from surgery to diagnosis of hydronephrosis was 47 months (20–70 months). Histology was invasive ductal carcinoma (IDC) in 6 cases and invasive lobular carcinoma (ILC) in 1 case. There were 6 bilateral cases and 1 unilateral case of hydronephrosis. The causes were retroperitoneal metastasis in 5 cases and lymph node metastasis in 2 cases. The hydronephrosis was untreated in 2 cases, and treated with a ureteral stent in 2 cases, nephrostomy in 1 case, and nephrostomy due to ureteral stent failure in 2 cases. The median survival from the onset of hydronephrosis was 12 months (3–57 months). Although the probability of hydronephrosis in breast cancer recurrence was not high, care must be taken to avoid renal dysfunction, infection, or pain, which may require treatment.