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Er der højere risiko for brystkræft ved Aubagio

Spørgsmål

Jeg fik konstateret brystkræft efter 2 år på Aubagio med nye attacks. Jeg blev udvasket af Aubagio efter anbefaling af neurologen. Som hun sagde, "jeg har stærk mistanke, at det er Aubagio der er synderen her". Jeg bliver nu fulgt med 2 scanninger om året.

Hvorfor står der intet i bivirkninger, at immundæmpende medicin - som Aubagio er - har en risiko for udvikling af kræft? Er det virkelig første prioritet for neurologer at udskrive medicin mod sclerose, velvidne at der en risiko for kræft, som ikke er nævnt i indlægssedlen?

Svar

Jeg kan godt forstå, at du undrer dig. Generelt er ønsket ved medicinsk behandling maksimal effekt uden bivirkninger, men det er næsten umuligt at opnå. Hvis man får brystkræft under en medicinsk behandling, er det nærliggende at tænke, at den spiller en rolle, men det siger ikke noget om at medicinen er årsagen. Under behandlingsforsøg og i “real life” behandling forekommer brystkræft, men det får jo hver 10. kvinde og over 70 procent af patienter med sclerose er kvinder.

På nettet fandt jeg denne lille rapport fra 2014 skrevet på en hjemmeside, der generelt informerer om multipel sclerose (MS). Den resumerer lidt om det man ved om brystcancer og MS. 

“May 22, 2014 | News | Living with MS
Multiple sclerosis and breast cancer

A frequent observation has been that people with multiple sclerosis generally have a lower risk of developing many forms of cancer compared to those in the general population (Nielsen and colleagues. Int J Cancer 2006;118:979-984; Lebrun and colleagues. Mult Scler 2008;14:399-405; Catala-Lopez and colleagues. Psychother Psychosom 2014;83:89-105). The reasons for this aren’t well understood.

One of the few exceptions is breast cancer. Women with MS appear to have a slightly higher risk of developing breast cancer compared to the non-MS population (Nielsen 2006; Midgard and colleagues. Acta Neurol Scand 1996;93:411-415; Sun and colleagues. Eur J Neurol 2014;21:238-244).

Why would women with MS have a higher risk of breast cancer?

Researchers have looked at various possible factors that may contribute to the risk. For example, women who have children earlier in life have a lower risk of breast cancer; conversely, breast cancer risk is higher for women who don’t have children or who have children later on. However, when these were taken into account, women with MS still had a higher rate of breast cancer (Nielsen 2006), suggesting that these lifestyle factors don’t play a major role.

Perhaps the most obvious factor to investigate is MS therapies – do they affect breast cancer risk? An important role of the immune system is to patrol the body looking for defective cells such as cancer cells, and MS therapies have the potential to alter this immune surveillance.

One study found that women with MS had a somewhat higher risk of breast cancer if they had been treated with immunosuppressive drugs (not the MS therapies commonly used) (Lebrun 2008). One analysis suggested an increased rate of breast cancer in women treated with Copaxone (Achiron and colleagues. Breast Cancer Res Treat 2005;89:265-270). As for the interferon drugs, one recent study reported a trend to a higher rate of breast cancer (Kingwell and colleagues. J Neurol Neurosurg Psychiatry 2014; epublished March 4, 2014), although an earlier study found no increased risk (Achiron 2005). According to the product labels, interferon use may be associated with a slightly higher rate of breast cancers, although this risk may decline over time; fibrous changes to the breast tissue may also occur. There is no evidence of an increased risk of breast cancer with newer drugs, such as Tysabri, Gilenya, Aubagio or Tecfidera”.