In the current study, the median survival time for all 185 patients with unresectable ductal pancreatic adenocarcinoma was only 119 days, which is about the same survival length reported by others [
5,
6]. The study showed that tumor size of the primary tumor as measured at the patient’s initial X-ray examination may predict survival length, especially if the presence of liver metastasis and gemcitabine therapy was taken into consideration and adjusted for in the Cox regression. Stricture length measured at ERCP was not a factor that could predict survival duration. Stricture length was divided into two groups (less than or equal to and greater than 2 cm) in 88 patients, and a survival analysis using the log rank test showed no significant difference at all, even when survival analysis was adjusted for gemcitabine in a Cox regression. Therefore, stricture length is an irrelevant prognosis factor for pancreatic cancer, and this has not been described previously. It is likely that the tumor grows asymmetrically and stricture length is a misleading indicator of the actual tumor size. If liver metastasis exists, patients have a significantly shorter survival compared with patients without primary liver metastasis. The difference was about 3 months. Even when the pancreatic tumor was less than 4.3 cm, there was a significant difference in survival time regarding liver metastasis or not. Tumor biology is certainly important and may partially explain the difference found between the groups. The findings are in accord with a recent German study where the only independent prognostic factor for shorter survival was distant metastasis [
7]. A multivariable approach was used to account for the functional form of the relationship between continuous prognostic variable factors and survival in advanced pancreatic cancer [
5]. The study investigated multiple clinical, histological, biochemical and demographic variables in the form of both binary and continuous measurements. The model confirmed five prognostic factors, namely albumin, CA19-9, alkaline phosphatase, lactate dehydrogenase and metastases; and also identified three additional possible prognostic factors as: leukocytes, aspartate aminotransferase and blood urea nitrogen. Reported hazard ratios were between 2.08 and 1.50. Tumor size was not included in the report, however, which our study identified as an important variable for predicting survival. Only early or late tumor stages were used, and no significant difference in survival time was found [
5]. Prognostic factors for survival have been described for patients who have undergone a surgical resection to treat their pancreatic cancer. But in the group of patients with advanced adenocarcinoma, detailed data on prognosis regarding tumor size and stricture length is lacking. Some studies have focused on the value of CT criteria in predicting survival rates for patients with potentially resectable pancreatic head carcinoma [
8,
9]. One of these studies included a small number of unresectable patients and showed a poor 4 month survival rate for these patients, but the only significant factors were whether the superior mesenteric artery was encased by the neoplasm or not and whether the tumor size was more than 3 cm [
8]. The results from another study suggested that baseline performance status activity and the occurrence of distant metastasis were the only variables that could be independently associated with predicting survival in patients with unresectable pancreatic carcinoma [
10]. In this study, the median survival was only 94 days compared to the 119 days found in the present study. This indicates that our study included patients with an advanced disease status and that survival was better predicted by using tumor size at the initial X-ray examination than relying on baseline performance status activity. Imaging studies play a crucial role in the diagnosis and management of patients with ductal pancreatic adenocarcinoma. Multislice CT is the most widely available and best-validated modality for imaging patients with pancreatic neoplasm. The sensitivity of CT for diagnosis of pancreatic adenocarcinoma, ranging 50–97%, and its positive predictive value for predicting unresectability, ranging 80 - 100%, are high but decreases for pancreatic lesions smaller than 1.5 to 2 cm [
11]. In our study, however, 29% of patients with unresectable cancer had tumors that could not be defined or measured. Newer CT machines with better image quality should make it easier to find small tumors. In the future, better CT or MRI computer protocols may improve the detection of pancreatic tumors but at present, semiautomatic computer programs are expected to render a measurement difference of > 10% between radiologists [
12]. Tumor volume as measured by different radiological methods and calculated as a square or bullet may lead to overestimations of tumor volume. It would be better to use programs that recognize the tumor in the pancreas and automatically calculate the volume. Parlak et al. assessed whether gross tumor volume determined by fusion of contrast-enhanced computerized tomography (CT) and 18 F-fluoro-deoxy-D-glucose positron emission tomography-CT (FDG-PET-CT) based radiotherapy could predict overall survival in 30 patients with advanced pancreatic neoplasm and found that a volume of 91 cm
3 corresponding to a tumor diameter of 5,58 cm predicted well survival [
13]. They found 16.3 vs. 9.5 months of survival difference. However survival rates were determined during radiotherapy and concurrent continuously infused 5-FU followed by 4 to 6 courses of maintenance gemcitabine and it is unclear if they adjusted for the treatment.