Fibroepithelial lesions (FELs) are a heterogeneous group of tumours comprising fibroadenomas (FAs) and phyllodes tumours (PTs). Here we used a 16-gene panel that was previously discovered to be implicated in pathogenesis and progression, to characterise a large international cohort of FELs via targeted sequencing. The study comprised 303 (38%) FAs and 493 (62%) PTs which were contributed by the International Fibroepithelial Consortium. There were 659 (83%) Asian and 109 (14%) non-Asian FELs, while the ethnicity of the rest was unknown. Genetic aberrations were significantly associated with increasing grade of PTs, and were detected more in PTs than FAs for MED12, TERT promoter, RARA, FLNA, SETD2, TP53, RB1, EGFR, and IGF1R. Most borderline and malignant PTs possessed ≥ 2 mutations, while there were more cases of FAs with ≤ 1 mutation compared to PTs. FELs with MED12 mutations had significantly higher rates of TERT promoter, RARA, SETD2, EGFR, ERBB4, MAP3K1, and IGF1R aberrations. However, FELs with wild-type MED12 were more likely to express TP53 and PIK3CA mutations. There were no significant differences observed between the mutational profiles of recurrent FAs, FAs with a history of subsequent ipsilateral recurrence or contralateral occurrence, and FAs without a history of subsequent events. We identified recurrent mutations which were more frequent in PTs than FAs, with borderline and malignant PTs harbouring cancer driver gene and multiple mutations. This study affirms the role of a set of genes in FELs, including its potential utility in classification based on mutational profiles.Conflict of interest statement: PHT, BTT, and PT jointly hold patent applications for PCT/SG2015/050107 (Breast fibroadenoma susceptibility mutations and use thereof) and PCT/SG2015/050368 (Method and kit for pathologic grading of breast neoplasms). The other authors declare no competing interests.

Fibroepithelial tumours are biphasic neoplasms of the breast comprising the common benign fibroadenomas and the less common phyllodes tumours (PTs), which have recurrent potential. PTs are classified into benign, borderline or malignant, based on five histopathological criteria, with malignant PTs having the highest metastatic capability. Accurate diagnosis can be challenging due to the subjective assessment of histopathological parameters. Fibroadenomas bear morphological similarities to benign PTs, while borderline and malignant PTs can sometimes be difficult to distinguish from other spindle cell tumours of the breast. From clonality studies to whole-genome sequencing, much research has been conducted to elucidate the molecular pathogenesis of fibroepithelial tumours, which, in turn, have allowed leveraging the findings for diagnostic applications, including grading of PTs. The most noteworthy discovery was of recurrent MED12 mutations in both fibroadenomas and PTs. Subsequent studies also uncovered relatively frequent genetic mutations in TERT promoter and RARA. A customised panel of 16 most frequently mutated genes in fibroepithelial tissues has been compiled previously and has contributed to resolving a few diagnostic dilemmas. This review will introduce the 16 genes and focus on the top three that are most frequently mutated in fibroepithelial tumours: MED12, TERT, and RARA.

Phyllodes tumours (PTs) of the breast are uncommon fibroepithelial neoplasms, comprising 0.3 -1.0% of all primary breast malignancies in Western countries, but accounting for a higher proportion of primary breast tumours in Asian countries. They are graded as benign, borderline or malignant based on the World Health Organisation (WHO) classification, according to a constellation of 5 histologic parameters. While most PTs carry a good prognosis, malignant and occasionally borderline PTs have the potential to metastasize to distant sites. Although events of distant metastasis are few, the prognosis for such patients is dismal, as they are often unresponsive to chemotherapy with high mortality. This review seeks to provide an overview of this rare but important phenomenon of distant metastases in PTs of the breast.

AimsHost immunity influences cancer progression and therapeutic response. We investigated the potential of tumour‐infiltrating lymphocytes (TILs) around ductal carcinoma in situ (DCIS) in predicting recurrence and progression.Methods and resultsCD4, CD8, programmed cell death 1 (PD‐1) and programmed cell death ligand 1 (PD‐L1) expression in DCIS from 198 patients was determined by immunohistochemistry. We correlated disease‐free survival (DFS), clinicopathological parameters and biomarker expression with TIL density and CD4/CD8 ratio. High TIL density was associated with high nuclear grade (P < 0.001), DCIS PD‐L1 expression (P = 0.008), TIL PD‐L1 expression (P < 0.001), oestrogen (ER) negativity (P < 0.001), progesterone (PR) negativity (P < 0.001), human epidermal growth factor receptor 2 (HER2) positivity (P = 0.002) and triple negativity (P = 0.001). TIL PD‐L1 expression was associated with triple‐negative DCIS (P = 0.028). TIL density was associated with molecular subtypes (P < 0.001). High CD4+ T cell density was associated with high nuclear grade (P = 0.001), microinvasion (P = 0.037), ER negativity (P < 0.001), PR negativity (P = 0.001), HER2 positivity (P = 0.004), triple negativity (P = 0.023) and PD‐L1 expression in TILs (P < 0.011). High CD4/CD8 ratio was associated with PD‐L1 expression in DCIS (P = 0.035) and TILs (P < 0.001). DCIS with higher TIL density disclosed worse DFS (P = 0.012) and was affirmed with multivariate analysis [95% confidence interval (CI) = 1.109–2.554, hazard ratio (HR) = 1.683, P = 0.014]. Poorer DFS for ipsilateral invasive recurrence was found for DCIS with higher CD4+ T cell density (P = 0.006) or CD4/CD8 ratio (P = 0.02), confirmed by multivariate analysis for the former (95% CI = 1.369–10.196, HR = 3.736, P = 0.01) and latter (95% CI = 1.311–7.935, HR = 3.225, P = 0.011).ConclusionDCIS with higher TIL density was associated with poorer prognostic parameters and predicted recurrence, while both CD4+ T cell density and CD4/CD8 ratio were associated with both recurrence and ipsilateral invasive recurrence.

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Sunitinib is a tyrosine kinase inhibitor used as first-line treatment for metastatic renal cell carcinoma (mRCC). Asian ethnicity has been previously associated with lower clearance and greater toxicities for sunitinib treatment, relative to Caucasian ethnicity. Research focusing on identifying corresponding biomarkers of efficacy and toxicity has been hitherto conducted in Caucasian populations, and few of the reported associations have been externally validated. Our work thus aims to investigate candidate biomarkers in Asian patients receiving sunitinib, comparing the observed genotype effects with those reported in Caucasian populations. Using data from 97 Asian mRCC patients treated with sunitinib, we correlated 7 polymorphisms in FLT3, ABCB1, VEGFR2, ABCG2 and BIM with patient toxicities, response, and survival. We observed a stronger association of FLT3 738T genotype with leucopenia in our Asian dataset than that previously reported in Caucasian mRCC patients (odds ratio [OR]=8.0; P=0.03). We observed significant associations of FLT3 738T (OR=2.7), ABCB1 1236T (OR=0.3), ABCB1 3435T (OR=0.1), ABCB1 2677T (OR=0.4), ABCG2 421A (OR=0.3) alleles and ABCB1 3435, 1236, 2677 TTT haplotype (OR=0.1) on neutropenia. Primary resistance (OR=0.1, P=0.004) and inferior survival (progression-free: hazard ratio [HR]=5.5, P=0.001; overall: HR=5.0, P=0.005) were associated with the ABCB1 3435, 1236, 2677 TTT haplotype. In conclusion, ABCB1 and FLT3 polymorphisms may be helpful in predicting sunitinib toxicities, response and survival benefit in Asian mRCC patients. We have also validated the association between FLT3 738T and sunitinib-induced leucopenia previously reported in Caucasian populations, but have not validated other reported genetic associations.

Breast cancer is the most common malignancy in Singapore women. Ductal carcinoma in situ (DCIS) is the putative, non-obligate precursor of the majority of invasive breast cancers. The efficacy of the Singapore breast-screening pilot project in detecting early stage breast cancer led to the launch of a national breast-screening programme, BreastScreen Singapore (BSS), in January 2002. In this study, we compared clinicopathological and immunohistochemical characteristics, as well as clinical outcomes, between screen-detected and symptomatic DCIS. The study cohort comprised 1202 cases of DCIS diagnosed at Singapore General Hospital from 1994 to 2010. Comparison of clinicopathological parameters, immunohistochemical results of ER, PR, HER2, CK14, EGFR, and 34βE12, and clinical outcomes was carried out between the 2 groups. Amongst 1202 cases, 610 (50.7%) were screen-detected and 592 (49.3%) were symptomatic DCIS. Screen-detected cases were smaller in size (P < 0.001), of lower nuclear grade (P = 0.004), and more frequently expressed ER (P < 0.001). Luminal A phenotype was more frequently observed in screen-detected DCIS, while triple-negative and HER2 phenotypes were more common in symptomatic DCIS (P < 0.001). The basal-like phenotype was also more frequent in symptomatic DCIS (P = 0.041). Mean and median follow-up was 99.7 and 97.8 months, respectively, with a maximum follow-up of 246.0 months. More symptomatic patients developed invasive recurrences compared to screen-detected patients (P = 0.001). A trend for better disease-free survival was observed in screen-detected patients (P = 0.076). Patients who were screen-detected experienced better overall survival than those with symptomatic DCIS (P = 0.007). Our data indicate a more favourable outcome of screen-detected DCIS patients confirming the role of BSS in early identification of this curable disease.

Phyllodes tumours (PTs) of the breast are uncommon fibroepithelial neoplasms comprising 0.3-1.0% of all primary breast tumours. The majority of PTs are benign and generally well managed with surgery. However, malignant PTs, and occasionally borderline PTs, can behave in a clinically aggressive manner by metastasizing to distant organs. Although distant metastasis is rare, the prognosis of patients with metastasis is dismal as many are unresponsive to standard chemotherapy and the risk of death is high. In this study, we correlated clinicopathological parameters to survival outcomes in a cohort of patients diagnosed with malignant PTs in our institution. The study cohort comprised 83 cases of malignant PTs diagnosed at the Department of Anatomical Pathology, Singapore General Hospital from 1994 to 2015. Clinicopathological features and follow-up were obtained from hospital records. Metastasis-free survival (MFS) and overall survival (OS) were estimated with the Kaplan-Meier method and compared between groups using the log-rank test. Cox regression was carried out to identify factors predictive for metastasis. Mean and median age of patients was 48 years (range 21-71 years). Tumour size measured from 30 to 220 mm (mean 90 mm, median 77 mm). Follow-up data was available for 68 patients. Mean and median follow-up was 90 and 57 months, respectively, with a maximum of 291 months. Distant metastasis occurred in 16 out of 68 patients (23.5%). The most common site of metastasis was the lung. Malignant heterologous elements were observed in 16 (19.3%) cases. Individual clinicopathological parameters had no impact on outcome. On Kaplan-Meier analysis, women with large tumours and presence of malignant heterologous elements showed trends for poorer MFS (p = 0.217 and p = 0.566, respectively). However, the combination of large tumours (≥ 90 mm) containing malignant heterologous elements disclosed significantly worse MFS (p = 0.043) and a trend for poorer OS (p = 0.238). On multivariate analysis, large tumours harbouring malignant heterologous elements independently predicted metastasis (95% CI 1.041-12.517, HR 2.434, p = 0.049). Our study demonstrates that tumour size and presence of malignant heterologous elements predicted metastasis in malignant PTs. Further work needs to be done in determining if protein biomarkers and genomic aberrations are able to additionally refine metastatic risk and define therapeutic targets.