Genetic susceptibility to breast cancer increases the risk of neutropenia and agranulocytosis: insights from Mendelian randomization

PURPOSE

The causal relationship between breast cancer and its estrogen receptor (ER) subtypes and neutropenia and agranulocytosis is unclear.

METHODS

In two-sample Mendelian randomization (MR), we used inverse variance weighting (IVW), Bayesian weighted MR (BWMR), MR-Egger, weighted median, simple mode, and weighted mode methods to analyze causality for ER-positive breast cancer, ER-negative breast cancer, overall breast cancer, and drug-induced neutropenia and agranulocytosis. To validate the results, we performed the analysis again using GWAS data on neutropenia from different databases. In multivariable MR (MVMR), we assessed the independent effects of ER-positive and ER-negative breast cancer on causality.

RESULTS

Two-sample MR analysis showed a causal relationship between ER-positive breast cancer (IVW odds ratio (OR) = 1.319, P = 7.580 × 10-10), ER-negative breast cancer (OR = 1.285, P = 1.263 × 10-4), overall breast cancer (OR = 1.418, P = 2.123 × 10-13), and drug-induced neutropenia and a causal relationship between ER-positive breast cancer (OR = 1.349, P = 1.402 × 10-7), ER-negative breast cancer (OR = 1.235, P = 7.615 × 10-3), overall breast cancer (OR = 1.429, P = 9.111 × 10-10), and neutropenia. Similarly, ER-positive breast cancer (OR = 1.213, P = 5.350 × 10-8), ER-negative breast cancer (OR = 1.179, P = 1.300 × 10-3), and overall breast cancer (OR = 1.275, P = 8.642 × 10-11) also had a causal relationship with agranulocytosis. MVMR analysis showed that ER-positive breast cancer remained causally associated with drug-induced neutropenia (OR = 1.233, P = 4.188 × 10-4), neutropenia (OR = 1.283, P = 6.363 × 10-4), and agranulocytosis (OR = 1.142, P = 4.549 × 10-3). Heterogeneity analysis and pleiotropy test showed that our results were reliable.

CONCLUSION

Our study provides genetic evidence for a causal association between breast cancer and its estrogen receptor subtypes and neutropenia. In clinical practice, in addition to focusing on therapeutic factors, additional attention should be given to breast cancer patients to avoid severe neutropenia.

Prospective cohort study of febrile neutropenia in breast cancer patients administered with neoadjuvant and adjuvant chemotherapies: CSPOR-BC FN study

Background

As Asians are more vulnerable to febrile neutropenia (FN) than Caucasians, evaluations of FN incidence and risk factors in Asians are important for the appropriate use of primary pegfilgrastim (PEG-G).

Patients and methods

Japanese breast cancer patients receiving standard adjuvant chemotherapies were prospectively enrolled in multicenter institutions from August 2015 to July 2017. FN was evaluated from 2 treatment policies: true FN (T-FN): ≥37.5 °C, grade 4 neutropenia, mandatory hospital visit (visiting); surrogate FN (S-FN): ≥37.5 °C, oral antibiotic, no mandatory visit (non-visiting). PEG-G was used at the physicians’ discretion. The primary endpoint was FN incidence during all cycles. Multivariate logistic regression analysis was performed to identify T-FN risk factors.

Results

Of 1005 enrolled patients, 980 women treated with FEC, E(A)C, and TC were analyzed. The FN incidence proportions in all patients were 22.5%, 27.5%, and 33.9% for FEC, E(A)C, and TC, respectively. Those of T-FN were 27.7%, 22.4%, and 36.6%; those of S-FN were 17.3%, 32.4%, and 31.5% with more frequent primary PEG-G usage. The relative dose intensity (RDI) of the 3 regimens was ≥0.85 in both groups. In the analysis of risk factors, TC (odds ratio = 2.67), age ≥ 65 years (2.24), and pretreatment absolute neutrophil count (ANC)/1000 μl (0.8) remained significant.

Conclusions

FN incidences were above 20% in the 3 regimens, with TC showing the highest. RDI was maintained at a high level in both visiting and non-visiting groups. Patient-related risk factors were age and pretreatment ANC.

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This study compared febrile neutropenia (FN) incidences of 3 breast cancer regimens.

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FN incidences were >20% in the 3 regimens (FEC, E(A)C; TC); TC showed the highest.

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The relative dose intensities in visiting and non-visiting groups were at high level.

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Age and pretreatment absolute neutrophil count were found as significant FN factors.

Febrile neutropenia and role of prophylactic granulocyte colony-stimulating factor in docetaxel and cyclophosphamide chemotherapy for breast cancer

PURPOSE

Febrile neutropenia (FN) incidence during docetaxel and cyclophosphamide (TC) chemotherapy, known as a high-risk regimen, differs among countries. The role of prophylactic granulocyte colony-stimulating factor (G-CSF) in FN is unclear. This study aimed to investigate FN frequency and relative dose intensity (RDI) of TC chemotherapy in patients with breast cancer and identify the correct population requiring prophylactic G-CSF.

METHODS

In total, 205 patients with breast cancer were scheduled for TC chemotherapy (docetaxel/cyclophosphamide 75/600 mg/m², every 3 weeks, 4 cycles) as adjuvant chemotherapy. Trastuzumab (8 mg/kg; continued with 6 mg/kg) was administrated intravenously for human epidermal growth factor receptor 2 (HER2)-positive cancer. Fifty-five patients received primary prophylactic measures (G-CSF: 20 and antibiotics: 35). We investigated the frequency of FN and hospitalization, RDI, and the factors related to FN, adverse events, hospitalization, and RDI.

RESULTS

FN occurred in 70 patients (35.7%). FN incidence was noted in 41.1% without any prophylactic measures and in 5.0% with prophylactic G-CSF. In multivariate analysis, the independent risk factors of FN were older age (≥ 60 years, P = 0.017) and without primary prophylactic G-CSF (P = 0.011). Eleven patients (5.6%) were hospitalized of which 8 (72.7%) were elderly. The median RDIs of docetaxel and cyclophosphamide were 96.7% and 99.7%, respectively.

CONCLUSION

FN frequency during TC chemotherapy was high, and primary prophylactic G-CSF reduced FN incidence. Primary prophylactic G-CSF is an effective therapy for preventing FN during TC chemotherapy. However, prophylactic G-CSF should be considered for elderly patients based on the low hospitalization rate and the high RDI.