Prognostic factors for gemcitabine-refractory patients with advanced pancreatic cancer: a retrospective analysis of a multicentre study (Anatolian Society of Medical Oncology)

Introduction

Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States [1]. Surgery is the only potentially curative treatment, while only 10–20% of these patients present with surgically resectable disease. Without effective treatment, the median survival for locally advanced disease is 8 to 12 months and only 3 to 6 months for metastatic disease. The overall 5-year survival rate among pancreatic cancer patients is still less than 5% [2–4].
Systemic chemotherapy with single-agent gemcitabine (Gem) is currently recommended as a standard first-line chemotherapy in pancreatic cancer patients [5–7]. Systemic chemotherapy for patients with advanced pancreatic cancer has limited impact on overall survival (OS), not merely due to low response rates, but also because of severe adverse effects [8–10]. Patients eligible for chemotherapy should be selected carefully. Very different prognostic factors in several trials have been identified for survival in patients with advanced pancreatic cancer [11–15].
Systemic chemotherapy with gemcitabine (Gem) or gemcitabine plus cisplatin (GemCis) is still considered the first choice, which presents a modest survival advantage. However, patients with advanced pancreatic cancer eventually experience disease progression and require second-line therapy. In spite of the clinical benefit of second-line treatments, the toxicity profile has long been observed with clinical interest. While there are reliable predictors to identify patients receiving first-line chemotherapy [11–15], very little knowledge is available about the prognostic factors in patients with Gem- or GemCis-refractory pancreatic cancer [16, 17]. Furthermore, it is necessary to properly treat patients with either additional chemotherapy or best supportive care. Nakachi et al. [16] suggest that performance status, peritoneal dissemination and C-reactive protein (CRP) levels were identified as important prognostic factors in patients with Gem-refractory pancreatic cancer.
We performed a multicentre retrospective analysis of prognostic factors in patients with Gem- or GemCis-refractory advanced pancreatic cancer.

Material and methods

Patient population

We retrospectively evaluated for pancreatic cancer in patients with Gem or GemCis-refractory advanced pancreatic cancer from February 2003 to October 2011. Gem- or GemCis-refractory pancreatic cancer was defined as pancreatic cancer with progression after chemotherapy with Gem or GemCis.
We retrospectively selected patients who met the following criteria: 1) ≥ 18 years old; 2) confirmed pathologically pancreatic adenocarcinoma; 3) chemotherapy and or radiotherapy naive; 4) progression of pancreatic cancer after chemotherapy; and 5) disease measured with the use of RECIST version 1.0 (Response Evaluation Criteria in Solid Tumours).
We retrospectively were selected carefully based on the following criteria: 1) they were 18 years or older in age; 2) they had histologic or cytologic diagnosis advanced pancreatic adenocarcinoma; 3) no previous chemotherapy or radiotherapy; 4) they were progresses after chemotherapy with Gem or GemCis; 5) they had to have measurable disease.

Treatment and assessment

Gem was administrated at 1000 mg/m² IV over 30 minutes on day 1 and 8 every 21-day schedule. Cisplatin was added to the gemcitabine schedule at 70 mg/m² on day 1 for every 21-day cycle. Tumour response was documented by computed tomography imaging according to the Response Evaluation Criteria in Solid Tumours (RECIST 1.0) at baseline and then every three cycles. Disease progression was defined as verification of progressive disease (PD) according to RECIST criteria or clinical deterioration of the patient’s general status.

Analysed variables as potential clinically relevant factors

Sixteen potential prognostic variables were chosen on the basis of previously published clinical trials. The variables were divided into two lines in each category: age (< 65 or ≥ 65 years), gender (male or female), performance status (0–1, 2–3), location of primary tumour (head or body-tail), grade (good, poor or moderate), stage (locally advanced or metastatic disease), first-line chemotherapy (Gem or GemCis), second-line chemotherapy (present or absent), the presence of diabetes mellitus at diagnosis, the presence of cholestasis at diagnosis, weight loss ≥ 10%, liver metastasis, lung metastasis, peritoneal dissemination, serum carcinoembryonic antigen (CEA) level (< 8.8 or ≥ 8.8 ng/ml) and serum carbohydrate antigen 19-9 (CA19-9) level (< 1000 or ≥ 1000 U/ml) at the time of first-line chemotherapy administration.

Statistical analysis

All of the analyses were performed using the SPSS statistical software program package (SPSS version 11.0 for windows). The differences of the clinical characteristics between the two groups were analysed by 2 test and student t test. Overall survival was calculated with the log-rank test. The Kaplan-Meier method was used for survival curves. Differences were assumed to be significant when the p value was less than 0.05.

Results

Patient characteristics

Between February 2003 and October 2011, 145 patients with Gem- or GemCis-refractory advanced pancreatic cancer were enrolled in this study. Seventy-six patients were treated with single-agent Gem. Sixty-nine patients were treated with GemCis. The median age of patients was 60.0 years (range 32–81) with 103 males and 42 females. Forty-one patients (33.1%) received second-line chemotherapy. The median OS was 7.0 months (Fig. 1). The patients’ baseline characteristics are listed in Table 1.

Prognostic factor analysis

The results of univariate analysis are summarised in Table 2. Among the sixteen clinical variables of univariate analysis, two variables were identified to have prognostic significance: liver metastasis (p = 0.004) and second-line chemotherapy (p = 0.001).
Multivariate analysis included the four prognostic significance factors in univariate analysis. The results of multivariate analysis are shown in Table 3. Multivariate analysis by Cox proportional hazard model showed that liver metastasis (p = 0.001) and second-line chemotherapy (p = 0.001) were considered independent prognostic factors for survival (Figs. 2, 3).

Discussion

Systemic chemotherapy for patients with pancreatic cancer has limited impact on OS due not only to low response rates, but also because of severe side effects. Without effective treatment, the median survival for locally advanced disease is 8 to 12 months and only 3 to 6 months for metastatic disease. The overall 5-year survival rate among pancreatic cancer patients is still less than 5% [2–4].
Patients eligible for chemotherapy should be selected carefully. This retrospective multicentre study analysed prognostic factors for survival in pancreatic cancer patients with Gem- or GemCis-refractory advanced pancreatic cancer.
On univariate analysis, four of sixteen potential factors were identified as significant prognostic factors for survival. However, three independent significant prognostic factors were found on multivariate analysis: location of primary tumour, liver metastasis and second-line chemotherapy.
To identify the prognostic factors of advanced pancreatic cancer before first-line chemotherapy, numerous clinical studies have been done [11–15]. However, very few studies were carried out for the prognostic factors in patients with Gem-refractory advanced pancreatic cancer [16, 17]. In these clinical studies, the location of the primary tumour was not evaluated. In our retrospective study, we found that the location of the primary tumour was not associated with regard to its prognostic importance for survival.
Liver metastasis was not found to be an independent prognostic factor for OS in patients with Gem-refractory advanced pancreatic cancer [16, 17], whereas in our retrospective study liver metastasis was associated with overall survival. The liver metastasis was associated with shorter survival due to several factors, among them delayed start of chemotherapy because of impaired liver function.
According to Maréchal et al. [17], second-line chemotherapy was found in univariate analysis, while multivariate analysis by Cox proportional hazard model did not show as an independent prognostic factor for survival in patients with Gem-refractory advanced pancreatic cancer. In this study, second-line chemotherapy was identified as an independent prognostic factor.
In conclusion, liver metastasis and second-line chemotherapy were identified as important prognostic factors in advanced pancreatic cancer patients refractory to treatment with Gem or GemCis. These prognostic factors may also facilitate pretreatment prediction of survival and could be used for selecting patients for treatment. Therefore, prospective and larger clinical trials are needed.

The authors declare no conflict of interests.

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Address for correspondence

Ali Inal MD
Department of Medical Oncology
Dicle University, School of Medicine
DiyarbakIr, Turkey
tel. 90 412 248 80 01
fax 90 412 248 84 40
e-mail: dr.ainal@gmail.com

Submitted: 23.02.2013
Accepted: 7.08.2013