Background: B-cell chronic lymphocytic leukemia (BCLL) in dogs generally is considered an indolent disease, but previous studies indicate a wide range in survival times.Objectives: We hypothesized that BCLL has a heterogeneous clinical course, similar to chronic lymphocytic leukemia in humans. We aimed to assess presentation and outcome in dogs with BCLL and evaluate the prognostic relevance of clinical and flow cytometric factors. Animals: One hundred and twenty-one dogs with BCLL diagnosed by flow cytometry. Three breed groups were represented: small breed dogs (n = 55) because of increased risk of BCLL; Boxers (n = 33) because of preferential use of unmutated immunoglobulin genes; and other breeds (n = 33). Methods: Retrospective study reviewing signalment, clinicopathologic data, physical examination findings, treatment, and survival of dogs with BCLL. Cellular proliferation, determined by the percentage of Ki67-expressing CD21+ B-cells by flow cytometry, was measured in 39 of 121 cases. Clinical and laboratory variables were evaluated for association with survival. Results:The median survival time (MST) for all cases was 300 days (range, 1-1644 days). Boxers had significantly shorter survival (MST, 178 days) than non-Boxers (MST, 423 days; P < .0001), and no significant survival difference was found between small breeds and other non-Boxer breeds. Cases with high Ki67 (>40% Ki67-expressing B-cells) had significantly shorter survival (MST, 173 days) than did cases with <40% Ki67 (MST undetermined; P = .03), regardless of breed. Cases with a high lymphocyte count (>60 000 lymphocytes/μL) or clinical signs at presentation had significantly shorter survival.Conclusions and Clinical Importance: B-cell chronic lymphocytic leukemia had a variable clinical course and Boxer dogs and cases with high Ki67 had more aggressive disease.

T‐cell lymphomas (TCL) are a diverse group of neoplasms with variable diagnostic features, pathophysiologies, therapeutic responses and clinical outcomes. In dogs, TCL includes indolent and aggressive tumours such as T‐zone lymphoma (TZL) and peripheral T‐cell lymphoma (PTCL), respectively. Delineation of molecular subtypes and investigation into underlying pathophysiologies of aggressive TCLs remains inadequate. We investigate the correlations between flow cytometry and histopathology of 73 cases of nodal TCL. The majority of cases (82.2%) were characterized as CD4+ TCL by flow cytometry. Fewer cases were classified as CD8+ TCL (6.8%) or CD4−CD8− TCL (11.0%). All cases, regardless of immunophenotype, exhibited conserved histologic features consistent with the WHO classification of PTCL. Histologic subsets of PTCL corresponding to immunophenotypic features were not identified. Neoplastic cell size determined by flow cytometry correlated significantly with mitotic rate. RNA‐seq was performed on a subset of CD4+ PTCL cases (n = 6) and compared with sorted control CD4+ T‐cells. The gene expression pattern of CD4+ PTCL was similar between all cases regardless of breed. PTCL was enriched in pathways representing G‐coupled protein receptor signalling, extracellular matrix remodelling and vascular development, immune signalling and mitotic activity. Furthermore, global gene expression changes were consistent with downregulation of PTEN signalling and upregulation of the MTOR‐PI3K‐ATK axis. In this study, we evaluated the correlations between flow cytometry, histopathology and gene expression within a large cohort of nodal TCLs. We further demonstrate the ability of flow cytometry to identify a subtype of T‐cell lymphoma, CD4+ PTCL, with a uniform histomorphology and gene expression profile.

Although younger women with breast cancer have the most to gain from receipt of optimal care, few data are available regarding their receipt of locoregional breast cancer treatments. We identified 317,596 women aged 18-64 who were diagnosed with invasive breast cancer at hospitals reporting to the National Cancer Database, a large national cancer registry, during 2004-2008. We used multivariable logistic regression to assess the association of patient age with mastectomy versus breast-conserving surgery (BCS), radiation with BCS, and postmastectomy radiation therapy (PMRT) with varying indications, adjusting for patient, clinical, and facility characteristics. Overall, 4 % of women were 35 years old or younger and 7 % were 36-40 years old. Women ≤age 40 were significantly more likely to have mastectomy than BCS compared with older women (57 % for age ≤35 and 52 % for ages 36-40 vs. 35 % for ages 61-64, adjusted odds ratio [OR] for age ≤35 = 2.03; 95 % confidence interval (CI) 1.93-2.14 and OR for ages 36-40 = 1.76; 95 % CI 1.69-1.84). Younger women were less likely to receive radiation if BCS was performed (69 and 73 vs. 80 %, OR for age ≤35 = 0.69; 95 % CI 0.65-0.74 and OR for ages 36-40 = 0.74; 95 % CI 0.70-0.78). For those who underwent mastectomy, overall rates of PMRT were low, although women ≤age 35 and ages 36-40 (vs. ages 61-64) were more likely to receive PMRT regardless of clinical indications. Our study suggests that young women with breast cancer may not be receiving optimal locoregional therapy. Efforts are needed to confirm these findings, further understand barriers to care, and increase the receipt of appropriate adjuvant radiation therapy among young women to improve their disease-free and overall survival.

Diffuse large B-cell lymphoma (DLBCL) is the most common haematopoietic malignancy in dogs. Recently, MYC and BCL2 expression levels determined with immunohistochemistry (IHC) were found to be prognostic in people with DLBCL. We hypothesized that canine DLBCL can be similarly subdivided into prognostic subtypes based on expression of MYC and BCL2. Cases of canine DLBCL treated with CHOP chemotherapy were retrospectively collected and 43 dogs had available histologic tissue and complete clinical follow-up. Median values of percent immunoreactive versus immunonegative cells were used to determine positive or negative expression status. Completion of CHOP was significantly associated with a positive outcome. Compared with human patients, our canine DLBCL patients had high IHC expression of both MYC and BCL2, and relative expression levels of one or both markers were not associated with clinical outcome.