Abstract
Histological ‘phenotypic subtypes’ that classify patients into four groups (immune, canonical, latent and stromal) have previously been demonstrated to stratify survival in a stage I–III colorectal cancer (CRC) pilot cohort. However, clinical utility has not yet been validated. Therefore, this study assessed prognostic value of these subtypes in additional patient cohorts along with associations with risk of recurrence and response to chemotherapy. Two independent stage I–III CRC patient cohorts (internal and external cohort) were utilised to investigate phenotypic subtypes. The primary endpoint was disease‐free survival (DFS) and the secondary endpoint was recurrence risk (RR). Stage II–III patients, from the SCOT adjuvant chemotherapy trial, were utilised to further validate prognostic value and for exploratory analysis assessing associations with adjuvant chemotherapy. In an 893‐patient internal cohort, phenotypic subtype independently associated with DFS (p = 0.025) and this was attenuated in stage III patients (p = 0.020). Phenotypic subtype also independently associated with RR (p < 0.001) in these patients. In a 146‐patient external cohort, phenotypic subtype independently stratified patients by DFS (p = 0.028), validating their prognostic value. In 1343 SCOT trial patients, the effect of treatment type significantly depended on phenotypic subtype (p interaction = 0.011). Phenotypic subtype independently associated with DFS in stage III patients receiving FOLFOX (p = 0.028). Furthermore, the immune subtype significantly associated with better response to FOLFOX compared to CAPOX adjuvant chemotherapy in stage III patients (p = 0.013). In conclusion, histological phenotypic subtypes are an effective prognostic classification in patients with stage III CRC that associates with risk of recurrence and response to FOLFOX adjuvant chemotherapy.
Highlights
There has been an enormous effort to develop a prognostic classification of colorectal cancer (CRC) based mainly on transcriptomic analysis of tumours [1,2]
We recently proposed a histological phenotypic subtyping method based on phenotypic characteristics of the tumour microenvironment and tumour proliferation [3], extrapolated from the consensus molecular subtypes (CMS), that could translate more readily to the clinic [1]
To ensure the hierarchy of the phenotypic subtype classification developed in the pilot study was robust, the three markers utilised were entered into multivariate analysis with KM grade (p = 0.002) and tumour stroma percentage (TSP) (p = 0.073) but not Ki67 (p = 0.971) demonstrated to be independently prognostic for disease-free survival (DFS)
Summary
There has been an enormous effort to develop a prognostic classification of colorectal cancer (CRC) based mainly on transcriptomic analysis of tumours [1,2]. We recently proposed a histological phenotypic subtyping method based on phenotypic characteristics of the tumour microenvironment (immune and stromal infiltrate) and tumour proliferation [3], extrapolated from the consensus molecular subtypes (CMS), that could translate more readily to the clinic [1] This method classifies into four prognostic groups – immune, canonical, latent and stromal – in a discovery cohort of 237 patients with stage I–III CRC [3], but requires validation. There is currently a lack of biomarkers to predict response to adjuvant chemotherapy, important for CRC and 5-FU-based adjuvant chemotherapy, as the SCOT trial recently demonstrated that patients receiving CAPOX (capecitabine and oxaliplatin) have similar survival with 3- versus 6-months duration, whereas patients receiving FOLFOX (bolus and infused fluorouracil with oxaliplatin) require 6-months duration [5].
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