Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Survival variability of controls and definition of imaging endpoints for longitudinal follow-up of pancreatic ductal adenocarcinoma in rats



The 3Rs guideline is the gold standard for ethics in animal experimentation. Two of those rules, namely refinement and reduction, require further improvement. The objective of this study was to define pathways to better compliance with these prerequisites. Two methods which move us in this direction are: (1) using small animal imaging techniques for pancreatic ductal adenocarcinoma (PDAC) follow-up and (2) reduction of the number of control animals included in a study of PDAC progression under treatment.

Materials and methods

Firstly, we used MicroCT scan to diagnose events showing PDAC progression prior to any clinical symptoms to thereby define more humane endpoints identifiable before any painful phenomenon is observed. Secondly, in order to test the hypothesis of using a reference control group in all preclinical studies of a new treatment of PDAC, we investigated the stability of the results obtained with the control groups in three successive identical studies comparing placebo and gemcitabine in tumor-bearing Lewis rats.


Two imaging endpoints were found. The first was the observation of a liver metastasis assessing PDAC diffusion and, earlier than liver metastasis, the presence of bands of fluid along the flanks, with more or less a medial displacement of bowel and solid viscera, reflecting a peritoneal ascites. Results of the longitudinal follow-up of rats in the gemcitabine study revealed heterogeneity in the survival rate in the three control groups, as opposed to the survival rate in the three treated groups which did not differ statistically. As a result, the significance of improved survival with chemotherapy varied greatly according to the control group used for the comparison, ranging from no impact to a highly significant effect.


The early detection by the means of animal imaging of one or more signs indicating the onset of a critical step in the development of the disease (e.g., ascites or/and metastasis) allows the researcher to prevent the occurrence of animal pain, thereby ensuring better animal welfare. However, using a single standard control group in an effort to use fewer animals for a given model runs such a significant risk of false results that it mars the entire study. Although reducing the number of animals in a study remains the gold standard of our experimental practice, in this case it would come at the price of a loss of validity of the results.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2


  1. Akladios CY, Bour G, Raykov Z, Mutter D, Marescaux J, Aprahamian M (2013) Structural imaging of the pancreas in rat using micro-CT: application to a non-invasive longitudinal evaluation of pancreatic ductal carcinoma monitoring. J Cancer Res Ther 1:70–76

  2. Angelova AL, Aprahamian M, Grekova SP, Hajri A, Leuchs B, Giese NA, Dinsart C, Herrmann A, Balboni G, Rommelaere J, Raykov Z (2009) Improvement of gemcitabine-based therapy of pancreatic carcinoma by means of oncolytic parvovirus H-1PV. Clin Cancer Res 15:511–519

  3. Animal Care Program (2016) MSU IACUC Guidelines by Topic. IG011: establishment of humane endpoints. Accessed 25 Feb 2016

  4. Martiniova L, Schimel D, Lai EW, Limpuangthip A, Kvetnansky R, Pacak K (2010) In vivo micro-CT imaging of liver lesions in small animal models. Methods 50:20–25

  5. Mutter D, Hajri A, Tassetti V, Solis-Caaxj C, Aprahamian M, Marescaux J (1999) Increased tumor growth and spread after laparoscopy vs laparotomy: influence of tumor manipulation in a rat model. Surg Endosc 13:365–370

  6. Tooth LA (2000) Defining the moribund conditions as an experimental endpoint for animal research. ILAR J 41:72–79

  7. Wallace J (2000) Humane endpoints and cancer research. ILAR J 41:87–93

Download references

Author information

Correspondence to Cherif Akladios.

Ethics declarations

Conflict of interest

Authors declare no conflict of interest.

Ethical approval

All applicable international, national, and institutional guidelines for the care and use of animals were followed. This article does not contain any studies with human participants performed by any of the authors.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Akladios, C., Ignat, M., Mutter, D. et al. Survival variability of controls and definition of imaging endpoints for longitudinal follow-up of pancreatic ductal adenocarcinoma in rats. J Cancer Res Clin Oncol 143, 29–34 (2017).

Download citation


  • Ductal adenocarcinoma
  • Humane endpoints
  • MicroCT scan
  • Pancreas
  • Rat
  • 3Rs