The doctoral dissertation in the field of Neurology will be examined at the Faculty of Health Sciences.
What is the topic of your doctoral research? Why is it important to study the topic?
The primary central nervous system lymphoma (PCNSL) has been a rare hematological disease, but several reports describe a growing incidence in Western countries. Optimal PCNSL follow-up protocol has been indefinite. The aim of this study was to assess incidence and mortality of PCNSL at population-based level in Finland, evaluate the rapid treatment onset impact on prognosis, and consider the timing of structured magnetic resonance imaging (MRI) benefit in PCNSL follow-up.
What are the key findings or observations of your doctoral research?
The average incidence of PCNSL in Finland was 0.68/100,000 person-years. The incidence was higher compared to other Nordic countries, and actually it was the highest in the world. PCNSL survival in Finland was better during 2013-2017 compared to 2007-2012, but overall, it was still poor especially in patients over 70 years of age. This is the first study to report population-based incidence and survival of PCNSL in Finland.
PCNSL prognosis was better if the treatment was started in three weeks following the first hospital visit compared to treatment onset after three weeks.
We discovered that structured imaging studies were beneficial for relapse detection during the first year after diagnosis. The clinical benefit of preplanned imaging decreased as follow-up time increased. There was a minor trend towards better overall survival after relapse for patients with relapse discovered via structured imaging compared to patients with relapse discovered via additional imaging based on patients’ new symptoms.
How can the results of your doctoral research be utilised in practice?
This thesis demonstrates high PCNSL incidence in Finland. Considering the poor prognosis, rapid treatment initiation is crucial for disease control. The major clinical benefit of structured imaging seems to materialize primarily during the first year after diagnosis. However, considering that the highest relapse risk occurs during the first two years after the end of therapy, we recommend that a structured MRI protocol could be used for two years after diagnosis for patients who are still able to receive curative PCNSL treatment.
What are the key research methods and materials used in your doctoral research?
We analysed Finnish Cancer Registry (FCR) data which included all PCNSL patients diagnosed between 2007 and 2017 in Finland. The data did not include any specific details concerning patients' previous comorbidities or given therapies for example.
From the other data, which were gathered retrospectively from eight hospitals in Finland, we assessed the impact of rapid treatment onset on PCNSL prognosis, and structured imaging benefit in PCNSL follow-up. This data included all details concerning given therapies, and the number and timing of relapses.
The doctoral dissertation of Inka Puhakka, Licentiate of Medicine, entitled Trends in incidence and prognosis of primary central nervous system lymphoma (PCNSL) in Finland with special reference to MRI in follow-up will be examined at the Faculty of Health Sciences. The Opponent in the public examination will be Docent Aki Hietaharju of Tampere University Hospital, and the Custos will be Professor Outi Kuittinen of the University of Eastern Finland. The public examination will be held in Finnish.
