Nunzio Digiacomo1, Elena Bolzacchini2, Giovanni Veronesi3, Roberta Cerutti4, Nora Sahnane5, Graziella Pinotti2, Marco Bregni6, Salvatore Artale6, Claudio Verusio6, Filippo Crivelli7, Carlo Capella1, Fausto Sessa4, Daniela Furlan4. 1. Unit of Pathology, Department of Medicine and Surgery, University of Insubria, Varese, Italy. 2. Unit of Oncology, ASST Sette Laghi, Varese, Italy. 3. Research Center in Epidemiology and Preventive Medicine (EPIMED), Department of Medicine and Surgery, University of Insubria, Varese, Italy. 4. Unit of Pathology, Department of Medicine and Surgery, University of Insubria, Varese, Italy; Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy. 5. Unit of Pathology, Department of Medicine and Surgery, University of Insubria, Varese, Italy; Research Center for the Study of Hereditary and Familial Tumors, Department of Medicine and Surgery, University of Insubria, Varese, Italy. Electronic address: nora.sahnane@asst-settelaghi.it. 6. Unit of Oncology, ASST Valle Olona, Varese, Italy. 7. Unit of Pathology, ASST Valle Olona, Varese, Italy.
Abstract
BACKGROUND: Approximately 10% of metastatic colorectal cancer (mCRC) cases will harbor the BRAF p.V600E mutation (BRAF-mCRC) and have been associated with a poor prognosis. Although they are usually considered a unique clinical entity, biologic heterogeneity has been described. We performed an extensive clinicopathologic study of a multicenter series of BRAF-mCRC to highlight differences between tumors with microsatellite instability (MSI) and microsatellite stable tumors, focusing on both inflammatory profiles and neuroendocrine differentiation. METHODS: We included 59 BRAF-mCRC cases and collected the clinical data (ie, surgery, treatment, and follow-up). We evaluated MSI status, budding, lympho-angioinvasion, neuroinvasion, extent of active stroma, CD3+ and CD8+ intratumoral and peritumoral lymphocytes, programmed cell death ligand 1, p53, Ki-67, synaptophysin, and CDX2 expression. RESULTS: The 22 MSI BRAF-mCRC cases were associated with the right side (P < .0001), an expansive grown pattern (P < .01), programmed cell death ligand 1 expression (P < .0001), high CD8 T-cell content (P = .0001), and lymph node metastases (P < .029). The 37 MSS BRAF-mCRC cases were characterized by a greater stromal component (P = .0002), pulmonary metastases (P = .095), and p53 and synaptophysin immunoreactivity (P = .004 and P = .001, respectively). Univariate analysis demonstrated that MSI and a high CD8 T-cell content were associated with a 34% (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.34-1.28; P = .2) and 33% (HR, 0.67; 95% CI, 0.45-0.99; P = .04) reduction in the risk of death, respectively. The combined presence of MSI and CD8 T-cell content decreased the hazard of mortality ≤ 63% (HR, 0.37; 95% CI, 0.14-0.97; P = .2), which was slightly reduced after multivariate analysis. CONCLUSION: A simultaneous evaluation of MSI, CD8 T-cell content, and neuroendocrine markers could allow for the identification of subsets of BRAF-mCRC with a different prognosis and potential eligibility for specific treatments.
BACKGROUND: Approximately 10% of metastatic colorectal cancer (mCRC) cases will harbor the BRAFp.V600E mutation (BRAF-mCRC) and have been associated with a poor prognosis. Although they are usually considered a unique clinical entity, biologic heterogeneity has been described. We performed an extensive clinicopathologic study of a multicenter series of BRAF-mCRC to highlight differences between tumors with microsatellite instability (MSI) and microsatellite stable tumors, focusing on both inflammatory profiles and neuroendocrine differentiation. METHODS: We included 59 BRAF-mCRC cases and collected the clinical data (ie, surgery, treatment, and follow-up). We evaluated MSI status, budding, lympho-angioinvasion, neuroinvasion, extent of active stroma, CD3+ and CD8+ intratumoral and peritumoral lymphocytes, programmed cell death ligand 1, p53, Ki-67, synaptophysin, and CDX2 expression. RESULTS: The 22 MSI BRAF-mCRC cases were associated with the right side (P < .0001), an expansive grown pattern (P < .01), programmed cell death ligand 1 expression (P < .0001), high CD8 T-cell content (P = .0001), and lymph node metastases (P < .029). The 37 MSS BRAF-mCRC cases were characterized by a greater stromal component (P = .0002), pulmonary metastases (P = .095), and p53 and synaptophysin immunoreactivity (P = .004 and P = .001, respectively). Univariate analysis demonstrated that MSI and a high CD8 T-cell content were associated with a 34% (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.34-1.28; P = .2) and 33% (HR, 0.67; 95% CI, 0.45-0.99; P = .04) reduction in the risk of death, respectively. The combined presence of MSI and CD8 T-cell content decreased the hazard of mortality ≤ 63% (HR, 0.37; 95% CI, 0.14-0.97; P = .2), which was slightly reduced after multivariate analysis. CONCLUSION: A simultaneous evaluation of MSI, CD8 T-cell content, and neuroendocrine markers could allow for the identification of subsets of BRAF-mCRC with a different prognosis and potential eligibility for specific treatments.