The impact of surgical volume on outcomes in newly diagnosed colorectal cancer patients receiving definitive surgeries

Colorectal cancer (CRC) patients who receive cancer surgeries from higher-volume providers may have better outcomes. However, the definitions of surgical volume may affect the results. We aim to analyze the effects of different definitions of surgical volume on patient outcomes. We conducted a nationwide population-based study in Taiwan that enrolled all patients who underwent definitive surgery for newly diagnosed CRC. We used three common definitions of surgical volume: total volume means the total surgical number conducted by the same provider during the study period; cumulative volume was calculated as the number of operations the surgeon performed before the index procedure; annual volume was calculated as the number of times the surgeon had been responsible for surgery during the index year. In this study, we included 100,009 newly diagnosed CRC patients, including 55.8% males, of median age 66 years at diagnosis (range 20-105 years). After adjustment for the patient and provider characteristics, we found that CRC patients receiving definitive surgery by higher-volume providers had better outcomes, especially where surgeon volume may play a more important role than hospital volume. The cumulative volume could predict the 5-year mortality of the study cohort better than the total and annual volume.

Clinical and Genotypic Insights Into Higher Prevalence of Palbociclib Associated Neutropenia in Asian Patients

BACKGROUND

CDK4/6 inhibitors (CDK4/6i) have shown great efficacy in prolonging progression-free survival and is the current standard of care for hormone positive (HR(+)) metastatic breast cancer (mBC). Despite well tolerability and ease of use, the most common side effect of CDK4/6i is myelosuppression, with neutropenia the most prevalent adverse effect. Studies show that the prevalence and severity of neutropenia are more marked in Asian patients, although details remain obscure.

METHODS

In this study, we retrospectively analyzed 105 Taiwanese patients who received palbociclib for HR(+) HER2(-) mBC at the Taipei Veterans General Hospital. To investigate a possible genetic association for high prevalence of neutropenia, we queried the Taiwan Biobank with publicly available germline databases (ALFA, gnomAD, ExAC, 1000 Genomes project, HapMap), for the allele frequencies of 4 neutropenia-related SNPs (ABCB1_rs1045642, ABCB1_rs1128503, ERCC1_rs3212986, ERCC1_rs11615) and compared between different ethnicities. In addition, one of the patients was a long-term patient with peritoneal dialysis. We quantified the levels of palbociclib in her serum and peritoneal fluid by liquid chromatography-mass spectrometry (LC-MS).

RESULTS

Interestingly, in our cohort, early neutropenia nadir (occurred within 56 days of start) was associated with worse treatment outcome, while occurrence of grade 3/4 neutropenia was associated with better outcome. We observed an extremely high incidence of neutropenia (96.2% any grade, 70.4% grade 3/4). In the analyzed germline databases, we discovered a higher SNP frequency of the T allele in ABCB1_rs1128503, a lower frequency of T allele in ABCB1_rs1045642, and a higher SNP frequency of G allele in ERCC1_rs11615. We observed that palbociclib levels in peritoneal dialysate ranged from around 20-50 ppb, and serum levels reached 100-110 ppb during drug administration and decreased to <10 ppb during discontinuation.

CONCLUSION

Our retrospective analysis of real world palbociclib use reveals an association with grade 3/4 neutropenia with better outcome and early neutropenia nadir with worse outcome. Our findings of Asian specific SNPs support a predisposition toward profound and prevalent neutropenia in Asian patients under CDK4/6i. We also report the first pharmacokinetics analysis on a patient with peritoneal dialysis receiving CDK4/6i. In summary, our study provides novel clinical and genotypic insights into CDK4/6i associated neutropenia.

Association of radiation dose to cardiac substructures with major ischaemic events following breast cancer radiotherapy

BACKGROUND AND AIMS

Patients with left-sided breast cancer receive a higher mean heart dose (MHD) after radiotherapy, with subsequent risk of ischaemic heart disease. However, the optimum dosimetric predictor among cardiac substructures has not yet been determined.

METHODS AND RESULTS

This study retrospectively reviewed 2158 women with breast cancer receiving adjuvant radiotherapy. The primary endpoint was a major ischaemic event. The dose-volume parameters of each delineated cardiac substructure were calculated. The risk factors for major ischaemic events and the association between MHD and major ischaemic events were analysed by Cox regression. The optimum dose-volume predictors among cardiac substructures were explored in multivariable models by comparing performance metrics of each model. At a median follow-up of 7.9 years (interquartile range 5.6-10.8 years), 89 patients developed major ischaemic events. The cumulative incidence rate of major ischaemic events was significantly higher in left-sided disease (P = 0.044). Overall, MHD increased the risk of major ischaemic events by 6.2% per Gy (hazard ratio 1.062, 95% confidence interval 1.01-1.12; P = 0.012). The model containing the volume of the left ventricle receiving 25 Gy (LV V25) with the cut-point of 4% presented with the best goodness of fit and discrimination performance in left-sided breast cancer. Age, chronic kidney disease, and hyperlipidaemia were also significant risk factors.

CONCLUSION

Risk of major ischaemic events exist in the era of modern radiotherapy. LV V25 ≥ 4% appeared to be the optimum parameter and was superior to MHD in predicting major ischaemic events. This dose constraint could aid in achieving better heart protection in breast cancer radiotherapy, though a further validation study is warranted.

Combination of palbociclib with enzalutamide shows in vitro activity in RB proficient and androgen receptor positive triple negative breast cancer cells

Objectives

Triple negative breast cancer (TNBC) lacks specific drug targets and remains challenging. Palbociclib, a cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor is approved for metastatic estrogen receptor (ER)-positive and human epithermal growth factor 2 (HER2)-negative breast cancer. The nature of cell cycle inhibition by palbociclib suggests its potential in TNBC cells. Retinoblastoma (RB, a known substrate of CDK4/6) pathway deregulation is a frequent occurrence in TNBC and studies have revealed that pharmacological CDK4/6 inhibition induces a cooperative cytostatic effect with doxorubicin in RB-proficient TNBC models. In addition, recent studies reported that anti-androgen therapy shows preclinical efficacy in androgen-receptor (AR)-positive TNBC cells. Here we examined the effect of palbociclib in combination with an anti-androgen enzalutamide in TNBC cells.

Method

MDA-MB-453, BT-549, MDA-MB-231 and MDA-MB-468 TNBC cell lines were used for in vitro studies. Protein expressions were assessed by Western blot analysis. Cytostatic effect was examined by MTT assay. Cell cycle and apoptosis were examined by flow cytometry.

Results

Palbociclib showed inhibitory effect in RB-proficient TNBC cells, and enzalutamide inhibited cell viability in AR-positive TNBC cells. Enzalutamide treatment could enhance the palbociclib-induced cytostatic effect in AR-positive/RB-proficient TNBC cells. In addition, palbociclib-mediated G1 arrest in AR-positive/RB-proficient TNBC cells was attenuated by RB knockdown.

Conclusion

Our study provided a preclinical rationale in selecting patients who might have therapeutic benefit from combining CDK4/6 inhibitors with AR antagonists.