Growth Pattern of Serous Cystic Neoplasms of the Pancreas: Observational Study with Long-term Magnetic Resonance Surveillance and Recommendations for Treatment

Background And Aims: The natural history and growth pattern of pancreatic serous cystic neoplasms (SCNs) are not well understood. This study was designed in order to get insight into the growth rate of SCNs and to suggest recommendations for their management.

Methods: Patients with well-documented incidentally discovered or minimally symptomatic SCNs who underwent yearly surveillance MRI were analysed using a linear mixed model. The growth rate and the effects of different fixed factors (sex, personal history of other non-pancreatic malignancies, radiological pattern, clinical presentation, tumour site) and random factors (age and tumour diameter at the time of diagnosis) on tumour growth were investigated.

Results: Study population consisted of 145 patients. Estimated overall mean growth rate was 0.28 cm/year, but the growth curve analysis showed a different trend between the first 7 years after the baseline evaluation (growth rate of 0.1 cm/year) and the subsequent period (years 7 to 10, growth rate of 0.6 cm/year, p<0.0001). Tests for fixed effects demonstrated that an oligocystic/macrocystic pattern and a personal history of other tumours are significant predictors of a more rapid mean tumour growth (p<0.0001 and 0.022, growth rates of 0.34 cm/year). Furthermore, tumour growth significantly increased with age (p = 0.0001).

Conclusion: Overall, SCNs grow slowly, and an initial non-operative approach is feasible in all the asymptomatic or minimally symptomatic patients. The oligocystic/macrocystic variant, a history of other non-pancreatic malignancies and patients' age impact on tumour growth. In any case, a significant growth is unlikely to occur before 7 years from the baseline evaluation. Tumour size at the time of diagnosis should not be used for decisional purposes.