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Have we ignored the sweetbread for long – Is it time to spare the pancreas?


1 Department of Radiation Oncology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Medical Oncology, All India Institute of Medical Sciences, New Delhi, India

Date of Submission29-Oct-2020
Date of Acceptance03-Jan-2021
Date of Web Publication22-Jun-2022

Correspondence Address:
Sorun Shishak,
Department of Radiation Oncology, All India Institute of Medical Sciences, New Delhi
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcrt.JCRT_1581_20



How to cite this URL:
Kaliyath SB, Shishak S, Rastogi S, Sharma D N. Have we ignored the sweetbread for long – Is it time to spare the pancreas?. J Can Res Ther [Epub ahead of print] [cited 2022 Jul 2]. Available from: https://www.cancerjournal.net/preprintarticle.asp?id=347788



Sir,

With advances in radiation delivery we have achieved highly conformal dose distribution to the target volumes while trying to spare the normal tissues. The concept of pancreas being a critical organ has been ignored since it was initially considered radioresistant to the effects of irradiation. Pancreas originally meant “sweetbread” in Greek when deranged results in impairment of glucose metabolism. Ever more diabetes mellitus (DM) would be considered co morbidity when patients are followed up and chronic pancreatitis (CP) symptoms attributed to after effects of radiation therapy (RT) to the small intestines in patients who have undergone abdominal RT. The first series of well-documented CP in 5 nonalcoholic patients with prior history of abdominal RT (4 Hodgkins, 1 Seminoma), was reported by Lévy et al. in 1993, where they noted a latent period of onset of CP and RT (6–24 years).[1] de Vathaire et al. conducted retrospective cohort analysis of 3468 childhood cancer survivors of which 65 DM were attributed to the effects of radiation dose according to gradient.[2] The relative risk of diabetes at 1 Gy was 1.61 (95% confidence interval 1·21–2·68) and there was dose response with exposure to tail of pancreas where the islet of Langerhans cells is concentrated, with the response reaching a plateau after 29 Gy. These results remain unchanged after adjustment for body mass index. Infradiaphragmatic RT also poses significant risk of DM in Hodgkin's Lymphoma survivors especially splenic radiation coupled with para-aortic strip radiation because of the close proximity to pancreas. Nimwegen et al. studied a cohort of patients where they found that the overall cumulative risk of DM at 30 years was 8.3% which increased to 14.2% with para-aortic radiation dose >36 Gy and the risk increased 2.3 fold if there was additional splenic radiation.[3] The aforementioned literature clearly demonstrates that there are consequent reactions when pancreas especially the tail region receives radiation with an exponential dose response. Volumetric decrease of pancreas after abdominal irradiation by 56% has recently been reported by Gemici et al.[4] Latest radiation techniques can be used to better spare the pancreas that can mitigate late effects especially in childhood survivors. Jouglar et al. compared conformal radiotherapy, helical tomotherapy, and proton beam therapy and showed that proton beam reduced the mean dose to the whole pancreas and the pancreatic tail without compromising Planning Target Volume (PTV) coverage.[5] Delineation of pancreas is a tedious process especially in children where paucity of retroperitoneal fat makes it difficult to distinguish from small bowel. Contouring pancreas as a whole or in different parts with differential dose constraints are still unresolved issues. More importantly due to the location, motion should be accounted for during delineation especially in superior-inferior direction which can be better accounted with four-dimensional computed tomography. In conclusion, this is a new avenue for further clinical research and pancreas should be considered as a critical organ that can be better spared with advanced radiation techniques thereby reducing the chronic effects of pancreatic radiation as patients especially children are expected to survive longer.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 > References Top

1.
Lévy P, Menzelxhiu A, Paillot B, Bretagne JF, Fléjou JF, Bernades P. Abdominal radiotherapy is a cause for chronic pancreatitis. Gastroenterology 1993;105:905-9.  Back to cited text no. 1
    
2.
de Vathaire F, El-Fayech C, Ben Ayed FF, Haddy N, Guibout C, Winter D, et al. Radiation dose to the pancreas and risk of diabetes mellitus in childhood cancer survivors: A retrospective cohort study. Lancet Oncol 2012;13:1002-10.  Back to cited text no. 2
    
3.
van Nimwegen FA, Schaapveld M, Janus CP, Krol AD, Raemaekers JM, Leontien CM, et al. Risk of diabetes mellitus in long-term survivors of Hodgkin lymphoma. J Clin Oncol 2014; 32:3257-63.  Back to cited text no. 3
    
4.
Gemici C, Yaprak G, Ozdemir S, Baysal T, Seseogullari OO, Ozyurt H. Volumetric decrease of pancreas after abdominal irradiation, it is time to consider pancreas as an organ at risk for radiotherapy planning. Radiat Oncol 2018;13:238.  Back to cited text no. 4
    
5.
Jouglar E, Wagner A, Delpon G, Campion L, Meingan P, Bernier V, et al. Can we spare the pancreas and other abdominal organs at risk? A comparison of conformal radiotherapy, helical tomotherapy and proton beam therapy in pediatric irradiation. PLoS One 2016;11:e0164643.  Back to cited text no. 5
    




 

 
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