Abstract Purpose We conducted a retrospective cohort study to examine whether neutropenia could be an indicator of good prognosis in patients treated with gemcitabine (GEM) for unresectable pancreatic cancer. Methods A total of 178 patients with unresectable pancreatic cancer, who were treated with first-line (n = 121) or second-line (n = 57) GEM, were included in our analyses. A Cox proportional hazard model was used to examine the effect of the grade of GEM-induced neutropenia on prognosis. Furthermore, the difference in survival time for each grade was assessed using a log-rank test. Results In the first-line population, the hazard ratios of patients with grade 2 or grade 3 neutropenia compared
with the ratios of those without neutropenia (grade 0) were 0.43 (95% CI 0.27–0.70) and 0.37 (0.21–0.65), respectively (p < 0.05). The median survival time (MST) was 3.8 months for grade 0, 9.4 months for grade 2, and 10.1 for grade 3. Landmark analysis of the second-line population revealed a hazard ratio of 0.52 (0.30–0.82) for grade 1 and 0.49 for grade 2 (0.28–0.72) (p < 0.05). MST was 1.3 months for grade 0, 4.7 months for grade 1, and 4.6 months for grade 2. Conclusions We found that neutropenia grade was an indicator of good prognosis in patients treated with firstline and second-line GEM for unresectable pancreatic cancer. A prospective study should be performed to examine whether dosage adjustment using neutropenia grade as an indicator would improve prognosis.
Keywords Unresectable pancreatic cancer · Neutropenia · Gemcitabin · Prognosis
Division of Physiology and Pathology, Department of Pharmacology, Toxicology and Therapeutics, Showa University School of Pharmacy, 1‑5‑8 Hatanodai, Shinagawa‑ku, Tokyo 142‑8555, Japan
Department of Hospital Pharmaceutics, Showa University School of Pharmacy, 1‑5‑8 Hatanodai, Shinagawa‑ku, Tokyo 142‑8555, Japan
Division of Medical Oncology, Department of Medicine, Showa University Koto-Toyosu Hospital, 1‑5‑8 Hatanodai, Koto‑ku, Tokyo 135‑0061, Japan
Health Service Center, Showa University, 1‑5‑8 Hatanodai, Shinagawa‑ku, Tokyo 142‑8555, Japan
Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, 1‑5‑8 Hatanodai, Shinagawa‑ku, Tokyo 142‑8555, Japan
Center of Pharmaceutical Education, School of Pharmaceutical Sciences, Showa University, 1‑5‑8 Hatanodai, Shinagawa‑ku, Tokyo 142‑8555, Japan
Introduction Pancreatic cancer (PC) is a malignant type of cancer with poor prognosis. The number of pancreatic cancer-related deaths per year is increasing worldwide and was estimated to be 226,000 individuals in 2008 . Resection is the only radical treatment for PC; however, at the time of diagnosis, approximately 80–95 % of cases are unresectable, with a 5-year survival rate of approximately 1 % . Therefore, the standard treatment in most PC patients is chemotherapy. Gemcitabine (GEM) is used as the standard chemotherapy for unresectable PC due to its ability to prolong survival and improve quality of life (QOL). Trials on combination therapy with GEM as well as several new agents have been conducted for more than 10 years, but survival
has been inadequately prolonged in all trials [3–11]. It has recently been reported that 5-fluorouracil/leucovorin combined with irinotecan and oxaliplatin (FOLFIRINOX) therapy  and GEM + nanoparticle albumin-bound paclitaxel (nab-PTX) combination therapy  improve survival. However, there is a high incidence of severe side effects with these regimens, and therefore, the indication of patients for such treatments should be limited. Consequently, GEM remains an important agent in the treatment of unresectable PC . As there are few drug options available for the treatment of unresectable PC, treatment with GEM is divided into first-line and second-line treatments, and continuation of this treatment while avoiding severe side effects is important to achieve better outcomes. On the other hand, in the late 1990s, it was reported that patients who developed neutropenia as a result of chemotherapy for breast cancer had good prognosis [15, 16]. Subsequent reports described similar outcomes for nonsmall cell lung cancer [17–19], gastric cancer , colorectal cancer [21, 22], and ovarian cancer [19, 23]. These reports suggest that neutropenia could be a predictive factor of treatment responsiveness. Neutropenia was a doselimiting toxicity (DLT) of all regimens in these reports, as was the case with the use of GEM. Although neutropenia is a potential predictive factor, as seen in GEM treatment, at present, the relationship between GEM-induced neutropenia and prognosis has not been examined. Furthermore, the relationship between prognosis and neutropenia in patients with unresectable PC undergoing chemotherapy has not been examined. Therefore, we conducted a retrospective cohort study to clarify whether neutropenia could be an indicator of good prognosis in patients treated with GEM for unresectable PC.
Materials and methods Patients and treatments From 2006 to 2012, patients diagnosed with unresectable PC at the Showa University Hospital, including 121 patients treated with first-line GEM and 57 patients treated with second-line GEM, were included in our study. Diagnosis of unresectable PC was made based on the comprehensive findings from ultrasonography, CT, MRI, endoscopic ultrasonography, endoscopic retrograde cholangiopancreatography, cytology, and histopathology. The clinical stage was determined on the basis of CT and MRI examination. All patients in this study has been administered the GEM in monotherapy and does not contain a combination therapy. The GEM schedule for 1 course involved drip
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infusion at a dose of 1000 mg/m2, administered once a week for 3 consecutive weeks, followed by a week of rest. The administration criteria for GEM were performance status (PS) below 2, neutrophil count ≥2000/μL, platelet count ≥100,000/μL, and hemoglobin ≥9.5 g/dL. This clinical study was approved by the Ethics Committee of the Showa University School of Medicine. Efficacy evaluation The primary endpoint in the present study was overall survival (OS). In the first-line population, OS was the period from diagnosis of unresectable PC to death. In the secondline population, OS was the period from the start of second-line treatment based on landmark analysis to death. Cases in which death was not confirmed were closed on October 31, 2013. In addition, the secondary endpoint was progression-free survival (PFS). PFS was defined as the period from the start of each treatment to discontinuation of treatment due to tumor growth or side effects. Clinical data and neutropenia The absolute neutrophil count (ANC) nadir during all GEM courses was classified from grade 0 to 4, with 0 indicating no neutropenia, in accordance with the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Neutrophil count was measured immediately before GEM administration on days 7 and 14, and depending on neutrophil count, additional measurements were occasionally taken. Granulocyte-colony-stimulating factor (G-CSF) was only administered if grade 4 neutropenia or febrile neutropenia developed, and this was not administered as preventive treatment. Data obtained at the time of unresectable PC diagnosis were collected from medical charts for examination of all factors. Factors involving blood tests were examined immediately prior to chemotherapy. The relative dose intensity (RDI) of GEM was calculated according to the method described by Dodwell et al. . Statistical analysis The effect of neutropenia grade on survival was examined by multivariate analysis using a Cox proportional hazard model (stepwise selection). We used six covariates, previously reported as prognostic factors, in multivariate analysis, i.e., PS, distal metastasis, CA19-9, CRP, Alb, and ANC [25–30]. Furthermore, the difference in the survival curve for each grade in patients undergoing first-line and second-line treatment was examined using a log-rank test (p < 0.05). Statistical analyses were performed using SPSS 20.0 J (IBM SPSS).
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Results Patient characteristics Table 1 lists the characteristics of the 121 patients and 57 patients who received first-line and second-line GEM, respectively. The first-line population included 67 men (55.4 %) with a median age of 64 years, and the second-line population included 28 men (49.1 %) with a median age of 66 years. Patient characteristics were similar between the first-line and second-line populations.
The survival curves and MSTs for each grade are shown in Fig. 2 and Table 3. A significant difference was observed among the OS curves for each grade (p < 0.05; log-rank test). MST for each grade was 3.8 months for grade 0, 9.4 months for grade 2, 10.1 months for grade 3, and 4.9 months for grade 4. Second‑line population
The median survival time (MST) and PFS in the first-line population were 7.6 and 3.9 months, respectively (Fig. 1). Neutropenia developed in 99 patients (81.8 %), including grade 1 in 18 patients (14.9 %), grade 2 in 40 patients (33.1 %), grade 3 in 31 patients (25.6 %), and grade 4 in 10 patients (8.3 %). The results of multivariate analysis are shown in Table 2. We found that neutropenia grade independently contributed to OS (p < 0.05). In comparison with grade 0, the hazard ratios for each grade (95% confidence interval) were as follows: 0.534 for grade 1 (0.320–0.792), 0.434 for grade 2 (0.270–0.698), 0.372 for grade 3 (0.214–0.646), and 0.772 for grade 4 (0.455–0.923) (p < 0.05).
Landmark analysis of the second-line population revealed that MST and PFS were 5.5 months and 3.4 months, respectively (Fig. 1). Neutropenia in the second-line population was grade 0 in 26 patients (45.6 %), grade 1 in 14 patients (24.6 %), grade 2 in 10 patients (17.5 %), grade 3 in 4 patients (7.0 %), and grade 4 in 3 patients (5.3 %). The results of multivariate analysis are shown in Table 2. We found that compared with grade 0, a significant difference was observed from grades 1 to 3, with a hazard ratio of 0.522 (0.301–0.822) for grade 1, 0.486 for grade 2 (0.284–0.716), and 0.588 for grade 3 (0.268–0.912) (p < 0.05). The survival curves and MSTs for each grade are shown in Fig. 3 and Table 3. A significant difference was observed among the survival curves for each grade (p < 0.05; logrank test). MST according to each grade was 3.3 months for grade 0, 6.4 months for grade 1, 6.7 months for grade 2, 5.6 months for grade 3, and 3.2 months for grade 4.
Table 1 Patients characteristics
Age, years Median (range) Sex Man/woman PS 0/1/2 Tumor location Head/body–tail Distant metastasis ANC (× 103/μL) Hb (g/dL) Plt (×104/μL) Alb (g/dL) T-bil (mg/dL) Cr (mg/dL) CRP (mg/dL) CA19-9
ANC absolute neutrophil count, PS performance status
Our group was the first to find that the onset of neutropenia in patients undergoing GEM therapy for unresectable PC was an indicator of good prognosis in first-line therapy. Similarly, it has been suggested that neutropenia is associated with good prognosis in first-line treatment for other types of cancers [15–25]. In addition, in the present study, all patients in the first-line treatment group exhibited prolonged OS for grades 1–3, with particularly good survival for grades 2 and 3. For grades 2 and 3, PFS was also significantly prolonged, and therefore, PFS prolongation was thought to contribute to the prolongation of OS. Furthermore, in the present study, we found that in second-line treatment, neutropenia was a good prognostic indicator. Based on the extent of our search of the literature, including studies on other cancer types, this is a new and important finding that demonstrates that neutropenia is associated with prognosis in second-line treatment. OS was greatly prolonged for grades 1 and 2 in second-line treatment, and when comparing MST among all patients, MST was extended by approximately 1 month. Similar to OS, the median PSF for grades 1 and 2 was extended by approximately 1 month. This suggests that the prolongation of PFS
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Fig. 1 Overall survival and progression-free survival of first-line population and secondline population. a Overall survival of 121 patients in first-line population. b Progression-free survival 121 patients in first-line population. c Overall survival of 57 patients in second-line population. d Progressionfree survival of 57 patients in second-line population. MST median survival time, PFS progression-free survival
in second-line treatment directly contributes to the prolongation of OS. In patients who receive standard treatment for unresectable PC, the survival period is short, and therefore, it is still not clear whether the second-line treatment itself contributes to the prolongation of OS. However, the results of the present study indicate that second-line GEM offers promising effects on survival. As limitation of retrospective studies, it is not excluded for the effects of additional treatment. In this study, there were many cases in which the administration of S-1 sequentially in additional treatment both first- and second-line population. Because it is considered to be verified separately from the effects of the additional administration of S-1, we are considering a new research. On the other hand, the OS of patients with grade 4 neutropenia was poorer than the OS of all patients overall in both the first-line and second-line populations; this result suggests that neutropenia itself is harmful to patients. In the grade 4 group, RDI and PFS were also low, and thus,
insufficient dose loading due to the prolongation of the rest period may have resulted in inadequate GEM therapy outcomes. Therefore, although mild neutropenia may be allowable, particular care should be taken to avoid grade 4 neutropenia. We have previously attempted to measure neutrophil count in patients with severe neutropenia prior to the start of GEM for unresectable PC . In patients at a high risk before treatment, therapy should be initiated at a low dosage; then, dose loading should be gradually increased by increasing the dosage and reducing the rest period (dose density). This enables severe side effects to be avoided and may maximize the potential therapeutic effects of GEM. In both the first- and second-line populations, survival was extremely poor in the grade 0 group. Surprisingly, OS was worse than that in the grade 4 group. RDI in the grade 0 groups in both the first- and second-line populations was maintained at approximately 90%, and an adequate dosage should be ensured. Previously, it was believed
Cancer Chemother Pharmacol (2015) 76:1217–1224 Table 2 Multivariate analysis of prognostic factors using Cox’s proportional hazards model
ANC absolute neutrophil count, PS performance status * p < 0.05 a
Hazard ratio versus grade 0
Hazard ratio per unit increase
Fig. 2 Comparison of the survival curves of overall survival and progression-free survival stratified by grade of neutropenia. a Overall survival of 121 patients treated with GEM at first-line therapy. b
Progression-free survival of 121 patients treated with GEM at firstline therapy. There was a significant difference in survival between the five groups by the log-rank test (p < 0.05)
that maintaining sufficient RDI was associated with good treatment outcomes ; however, this was not always the case in GEM for unresectable PC. It was reported that a phase I trial to establish the dose-limiting toxicity (DLT) of anticancer agents was conducted with a minimum number of subjects, and therefore, there were individual differences between the maximum tolerated dose and the
recommended dose [33, 34]. In some patients, the set GEM dosage in the standard treatment for unresectable PC was inadequate, suggesting that good outcomes were not obtained in patients not reaching the optimal dosage. The use of neutropenia grade as an indicator may help yield better outcomes from GEM by increasing dose loading according to the individual.
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Table 3 Survival times and relative dose intensity of each neutropenia groups Grade of neutropenia
MST median survival time, PFS progression-free survival, RDI relative dose intensity
Studies to date have shown that neutrophils invade tumors, promoting the acceleration of angiogenesis and suppressing the anti-tumor immune response, thereby speeding up tumor proliferation [35–38]. We posit that neutropenia is an indicator for good prognosis because neutrophils are damaged by anticancer agents and may be associated with the inhibition of tumor proliferation. In support of this, the present study found using multivariate analysis that in the first-line population, ANC was an independent factor that contributed to prognosis. The relationship
Fig. 3 Landmark analysis of overall survival and progression-free survival compared among the five groups stratified by neutropenia grade. a Overall survival of 57 patients treated with GEM for secondline therapy. b Progression-free survival of 57 patients treated with
between increased neutrophils and tumor progression should be examined in more detail in future studies. Although the number of subjects in the present study was small, we were able to confirm that in first-line and second-line therapy, the survival curve differed according to neutropenia grade. Earlier reports of other cancer types similarly considered grades 3 and 4 neutropenia as severe. In the present study, by dividing subjects into 5 grades for analysis, we found that OS deteriorated in patients with grade 4 neutropenia, whereas in patients with grade 3 neutropenia, OS improved despite grade 3 being considered as severe neutropenia. However, the results show a decrease in the number of patients in each group. Therefore, to strengthen the hypothesis that neutropenia is a useful predictive factor of prognosis, additional analyses are needed with a larger population. In this study, grade of neutropenia has been using nadir during all GEM courses similar to the methodology of other studies [17–23]. Among the 99 subjects who experienced neutropenia in the first-line population, 71 patients (72 %) have reached the nadir in neutropenia of first course, and 89 (90 %) patients have reached the nadir until the second course. Similarly, among the 44 patients who experienced neutropenia in the second-line population, 35 patients (80 %) have reached the nadir in neutropenia of first course, and 39 (89 %) subjects have reached the nadir until the second course. Therefore, we thought that it is possible to modify the treatment of early of course. However, in the case that it reaches the nadir late course, impact of cumulative dose is not clear. It requires additional examination whether to improve the
GEM for second-line therapy. There was a significant difference in survival between the five groups as determined by the log-rank test (p < 0.05)
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prognosis by reaching the target grade neutropenia at an early course. GEM is administered with a weekly schedule and thus compared with monthly schedules, and it is relatively easier to adjust dosage and to avoid severe neutropenia. Consequently, adjustment of GEM dosage using neutropenia as an indicator is highly feasible compared with adjustment of other regimens. The intervention trial design to adjust the dose for each administration, it is considered to be able to prove this hypothesis a more robust. We hope that further examinations with interventional trials that demonstrate the efficacy of neutropenia as an indicator for GEM dosage adjustment will be greatly beneficial to patients with unresectable PC, who have few effective treatment options. Acknowledgments We thank Jun Kawazoe, Emi Katsumoto, Wakana Kato, Saori Mochida, Megumi Mori, who are students at the Showa University School of Pharmacy, for their technical assistance.
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