Cancer risk raised in multiple sclerosis
A study from Norway presented at the recent European Academy of Neurology congress (EAN 2019) has hinted at a possible increased risk of cancer among patients diagnosed with multiple sclerosis (MS).
“MS was associated with increased risk of cancer in urinary, respiratory, and [central nervous system (CNS)] organs,” said the researchers.
The researchers of this prospective, longitudinal cohort study utilized the Norwegian MS Registry, prevalence studies, and the Norwegian Cancer Registry to identify 6,883 patients with MS born between 1930 and 1979 and compared them with their siblings without MS (n=8,918) as well as a control group comprising a non-MS population (n=37,919).
Over the 65-year follow-up period, patients with MS had a 14 percent higher risk of cancer compared with the control group without MS (hazard ratio [HR], 1.14, 95 percent confidence interval [CI], 1.05–1.23). [EAN 2019, abstract O1204]
This elevated risk was particularly evident pertaining to respiratory cancers with a 66 percent increased risk over non-MS controls (HR, 1.66, 95 percent CI, 1.26–2.19), as well as a 51 and 52 percent increased risk, respectively, of urinary (HR, 1.51, 95 percent CI, 1.12–2.04) and CNS cancers (HR, 1.52, 95 percent CI, 1.11–2.09).
However, patients with MS did not have a higher risk of cancer compared with their siblings without MS (HR, 0.92, 95 percent CI, 0.83–1.03), owing to an 82 percent elevated risk of haematological cancers in the siblings compared with the MS patients (HR, 1.82, 95 percent CI, 1.21–2.73), in particular lymphoma (HR, 1.75), myeloma (HR, 1.98), and leukaemia (HR, 1.56). Siblings without MS also had a 72 percent elevated risk of haematological cancers compared with the non-MS controls (HR, 1.72, 95 percent CI, 1.36–2.18), specifically lymphoma (HR, 1.49), myeloma (HR, 2.04), and leukaemia (HR, 1.62).
The increased risk of haematological cancers among siblings without MS points to the possibility of a “shared aetiology” between haematological cancer and MS, said study lead author Dr Nina Grytten from Haukeland University Hospital, Bergen, Norway, and co-authors.
“Additional research could … identify the possible connections between haematological cancer and MS and new ways in which we could manage these conditions,” she said.
The researchers acknowledged the potential limitations of the study including surveillance bias as well as the impact of lifestyle factors such as smoking on cancer incidence.
“Previous clinical studies of cancer risk in MS patients in various countries have shown inconsistent findings, so further research [was] needed to help improve our understanding in this area,” said Grytten. [Int J Cancer 2006;118:979-984; Mult Scler 2015;21:294-304]
“This study is the first to compare cancer risk in MS with non-affected siblings of MS patients. The risk assessment between these two groups is extremely interesting because they share the same genetics and environmental conditions,” she said.
“This research outlines the need for greater awareness of cancer risk among MS patients, which should lead to shortened cancer diagnosis and more effective therapy in order to improve outcomes and survival,” she added.