{"id":6418,"date":"2026-10-19T09:48:53","date_gmt":"2026-10-19T09:48:53","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-laeknavisindum-arnar-snaer-agustsson\/"},"modified":"2026-10-19T09:48:53","modified_gmt":"2026-10-19T09:48:53","slug":"doktorsvorn-i-laeknavisindum-arnar-snaer-agustsson","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-laeknavisindum-arnar-snaer-agustsson\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed l\u00e6knav\u00edsindum – Arnar Sn\u00e6r \u00c1g\u00fastsson"},"content":{"rendered":"
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F\u00f6studaginn 3. okt\u00f3ber 2025 ver Arnar Sn\u00e6r \u00c1g\u00fastsson doktorsritger\u00f0 s\u00edna \u00ed l\u00e6knav\u00edsindum vi\u00f0 L\u00e6knadeild H\u00e1sk\u00f3la \u00cdslands. Ritger\u00f0in ber heiti\u00f0: \u00c1hrif bl\u00f3\u00f0\u00feynningar- og b\u00f3lguey\u00f0andi lyfja \u00e1 horfur einstaklinga me\u00f0 ristil- og enda\u00fearmskrabbamein: l\u00fd\u00f0grundu\u00f0 ranns\u00f3kn. Impact of anticoagulation and immunosuppressive drugs on the prognosis of patients with colorectal cancer: a population-based study.<\/p>\n

Andm\u00e6lendur eru dr. Martti Farkkila, pr\u00f3fessor emeritus vi\u00f0 H\u00e1sk\u00f3lann \u00ed Helsinki, og dr. Richard Goldberg, pr\u00f3fessor vi\u00f0 West Virginia University School of Medicine \u00ed Bandar\u00edkjunum.<\/p>\n

Umsj\u00f3narkennari og lei\u00f0beinandi var Einar Stef\u00e1n Bj\u00f6rnsson, pr\u00f3fessor og me\u00f0lei\u00f0beinandi var J\u00f3hann P\u00e1ll Hreinsson, s\u00e9rfr\u00e6\u00f0ingur. Auk \u00feeirra s\u00e1tu \u00ed doktorsnefnd \u00c1sger\u00f0ur Sverrisd\u00f3ttir, s\u00e9rfr\u00e6\u00f0ingur, Helgi Birgisson, s\u00e9rfr\u00e6\u00f0ingur, Sigr\u00fan Helga Lund, pr\u00f3fessor og Sigurd\u00eds Haraldsd\u00f3ttir, pr\u00f3fessor.<\/p>\n

S\u00e6d\u00eds S\u00e6varsd\u00f3ttir, pr\u00f3fessor og deildarforseti L\u00e6knadeildar, stj\u00f3rnar ath\u00f6fninni sem fer fram \u00ed H\u00e1t\u00ed\u00f0asal H\u00e1sk\u00f3la \u00cdslands og hefst kl. 9.00.<\/p>\n

\u00c1grip <\/strong><\/p>\n

N\u00fdgengi ristil- og enda\u00fearmskrabbameina fer vaxandi og eru \u00feau ein algengasta d\u00e1narors\u00f6k af v\u00f6ldum krabbameina. Ristil- og enda\u00fearmskrabbamein greinast oftast me\u00f0 bl\u00e6\u00f0ingartengdum einkennum og fyrri ranns\u00f3knir hafa s\u00fdnt fram \u00e1 a\u00f0 bl\u00f3\u00f0\u00feynningarlyf geti auki\u00f0 l\u00edkur \u00e1 \u00feeim bl\u00e6\u00f0ingum. Hins vegar hefur ekki veri\u00f0 rannsaka\u00f0 hvort bl\u00f3\u00f0\u00feynningarlyf geti leitt til snemmgreiningar og \u00fe\u00e1 betri lifunar. Ranns\u00f3knir hafa s\u00fdnt fram \u00e1 a\u00f0 hjartamagn\u00fdl er verndandi gegn ristil- og enda\u00fearmskrabbameinum en hafa gefi\u00f0 misv\u00edsandi ni\u00f0urst\u00f6\u00f0ur um \u00e1hrif \u00feess \u00e1 lifun vegna krabbameina. \u00deekkt er a\u00f0 sterar draga \u00far b\u00f3lgu og hafa v\u00ed\u00f0fe\u00f0m \u00e1hrif \u00e1 \u00f3n\u00e6miskerfi\u00f0, en \u00e1hrif steranotkunar fyrir greiningu \u00e1 ristil- og enda\u00fearmskrabbameinum hafa l\u00edti\u00f0 veri\u00f0 ranns\u00f6ku\u00f0 og \u00fe\u00e1 ekki \u00e1hrif \u00feeirra \u00e1 lifun.<\/p>\n

Allar fj\u00f3rar ranns\u00f3knirnar voru l\u00fd\u00f0grunda\u00f0ar afturskyggnar ranns\u00f3knir sem bygg\u00f0ust \u00e1 gagnagrunnum. \u00cd fyrstu ranns\u00f3kninni var n\u00fdttur bl\u00f3\u00f0\u00feynningargagnagrunnur til a\u00f0 kanna orsakir meltingarvegsbl\u00e6\u00f0inga, fr\u00e1 2014-2019. Hinar \u00ferj\u00e1r ranns\u00f3knirnar voru bygg\u00f0ar \u00e1 ristils- og enda\u00fearmskrabbameins-gagnagrunni yfir alla sj\u00faklinga sem greindust me\u00f0 ristil- og enda\u00fearmskrabbamein fr\u00e1 2000-2019 \u00e1 \u00cdslandi og borin var saman lyfjanotkun fyrir greiningu og \u00fatkomur vegna krabbameins.<\/p>\n

Ni\u00f0urst\u00f6\u00f0ur fyrstu ranns\u00f3knarinnar s\u00fdndu fram \u00e1 a\u00f0 hj\u00e1 einstaklingum sem t\u00f3ku bl\u00f3\u00f0\u00feynningarlyf og fengu meltingarvegsbl\u00e6\u00f0ingu stafa\u00f0i bl\u00e6\u00f0ingin oftar af sepa \u00ed ristli e\u00f0a krabbameini. \u00cd annarri ranns\u00f3kninni kom \u00ed lj\u00f3s a\u00f0 bl\u00f3\u00f0\u00feynningarh\u00f3purinn haf\u00f0i verri heildarlifun en hins vegar betri krabbameinstengda lifun, \u00fe\u00f3 svo a\u00f0 stigun hafi ekki veri\u00f0 markt\u00e6kt fr\u00e1brug\u00f0in. \u00deetta gefur til kynna a\u00f0 bl\u00f3\u00f0\u00feynningarlyf \u00fatleysi frekar bl\u00e6\u00f0ingar fr\u00e1 sepa e\u00f0a krabbameini \u00ed ristli og geti leitt til betri lifunar, a\u00f0 \u00f6llum l\u00edkindum \u00ed gegnum snemmgreiningu en frekari ranns\u00f3kna er \u00fe\u00f6rf.
\u00deri\u00f0ja ranns\u00f3knin \u00e1 hjartamagn\u00fdli fyrir greiningu ristil- og enda\u00fearmskrabbameins s\u00fdndi a\u00f0 einstaklingar sem t\u00f3ku hjartamagn\u00fdl greindust mun sjaldnar me\u00f0 meinvarpandi sj\u00fakd\u00f3m og h\u00f6f\u00f0u betri krabbameinstengda lifun. Hjartamagn\u00fdl vir\u00f0ist \u00fev\u00ed hafa hindrandi \u00e1hrif \u00e1 meinv\u00f6rpun krabbameins. A\u00f0 lokum voru \u00e1hrif stera ranns\u00f6ku\u00f0 \u00e1 lifun einstaklinga me\u00f0 ristil- og enda\u00fearmskrabbamein en \u00fear kom \u00ed lj\u00f3s a\u00f0 \u00feeir sem t\u00f3ku stera voru l\u00edklegri til a\u00f0 f\u00e1 endurkomu krabbameins e\u00f0a l\u00e1tast yfir t\u00edmabili\u00f0. \u00deessi \u00e1hrif virtust einkum koma fram fimm \u00e1rum eftir upphafsgreiningu en \u00feessar ni\u00f0urst\u00f6\u00f0ur \u00fearf a\u00f0 sta\u00f0festa \u00ed fleiri ranns\u00f3knum.<\/p>\n

Abstract <\/strong><\/p>\n

The incidence of Colorectal Cancer (CRC) is increasing, and it\u2018s one of the leading causes of death due to cancer. The most common presenting symptoms of CRC are gastrointestinal bleeding events, and oral anticoagulants have been shown to increase the risk of such events. However, there are no studies examining whether oral anticoagulants (OACs) could improve survival through potential early detection. Aspirin has been demonstrated to have protective effects against CRC, but its impact on cancer-specific survival has been conflicting. Aspirin\u2018s effects are believed to be mediated through anti-inflammation. Corticosteroids have multiple and complex effects on inflammation and the immune system, but their potential effects on CRC have not been previously explored.<\/p>\n

All four studies were nationwide studies based on retrospective cohort databases. Study I used data from the OAC prescriptions database to examine gastrointestinal bleeding events in OAC users from 2014 to 2019. Studies II, III, and IV were based on the Colorectal Cancer Database from 2000 to 2019 and compared the association of pre-diagnostic medications with CRC outcomes.<\/p>\n

Study I demonstrated that OACs increased the risk of bleeding events due to either colonic adenoma or CRC. Anticoagulation use was associated with improved CRC-specific survival, while overall survival was decreased in OAC users. Both of these results further suggest that anticoagulation could potentially lead to early CRC detection with improved CRC-survival. Aspirin users had improved CRC-specific survival, mediated mainly by fewer patients with stage IV disease. This could mean that aspirin could delay or hinder the metastatic development of CRCs. Corticosteroid use prior to CRC diagnosis was associated with worse disease-free survival, with the decreased survival mostly seen 5 years after cancer diagnosis. This could imply that corticosteroids might have negative effects on long-term cancer survival; however, further studies are required to substantiate these findings.<\/p>\n

Um doktorsefni<\/strong><\/p>\n

Arnar Sn\u00e6r \u00c1g\u00fastsson er f\u00e6ddur \u00e1ri\u00f0 1993 \u00e1 Akranesi og uppalinn \u00ed V\u00edk \u00ed M\u00fdrdal. Hann lauk n\u00e1mi af n\u00e1tt\u00farufr\u00e6\u00f0ibraut Menntask\u00f3lans a\u00f0 Laugarvatni og s\u00ed\u00f0an emb\u00e6ttispr\u00f3fi \u00ed l\u00e6knisfr\u00e6\u00f0i 2020. A\u00f0 loknu kand\u00eddats\u00e1ri h\u00f3f hann s\u00e9rn\u00e1m \u00ed sv\u00e6fingar- og gj\u00f6rg\u00e6slul\u00e6kningum vi\u00f0 Landsp\u00edtala \u00fear sem hann starfar samhli\u00f0a doktorsn\u00e1mi. \u00c1 kand\u00eddats\u00e1ri h\u00f3f Arnar doktorsn\u00e1m vi\u00f0 H\u00e1sk\u00f3la \u00cdslands og hlaut styrk fr\u00e1 Eimskipasj\u00f3\u00f0i H\u00e1sk\u00f3la \u00cdslands. Foreldrar Arnars eru \u00c1g\u00fast Freyr Bjartmarsson og Krist\u00edn Svafarsd\u00f3ttir.<\/p>\n<\/div><\/div>","protected":false},"featured_media":5805,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2025-10-03T09:00:00+00:00","_phd_date_end":"2025-10-03T12:00:00+00:00","_phd_location":"A\u00f0albygging H\u00e1t\u00ed\u00f0asalur","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"\u00c1hrif bl\u00f3\u00f0\u00feynningar- og b\u00f3lguey\u00f0andi lyfja \u00e1 horfur einstaklinga me\u00f0 ristil- og enda\u00fearmskrabbamein: l\u00fd\u00f0grundu\u00f0 ranns\u00f3kn. 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