Fræðigrein

Föstudaginn 6. maí síðastliðinn varði Tómas Guð­bjarts­son doktorsritgerð sína við læknadeild Há­skóla Íslands. Ritgerðin er um nýrnafrumukrabba­mein og ber heitið Renal Cell Carcinoma in Iceland: Incidence, prognosis, inheritance and treatment. Andmælendur voru Jón Gunnlaugur Jónasson, dósent og yfirlæknir Krabbameinsskrár KÍ og prófessor Börje Ljungberg í Umeå í Svíþjóð. Athöfninni stýrði Stefán B. Sigurðsson deildar­forseti læknadeildar. Það færist nú smám saman í vöxt að íslenskir læknar taki doktorspróf frá HÍ. Þeir Magnús Gottfreðsson, Ólafur Baldursson og Davíð O. Arnar eru allir með íslenskt doktorspróf.

Hér fer á eftir enskt ágrip doktorsritgerðarinnar.

Renal Cell Carcinoma (RCC) is by far the most common malignant tumor of the kidney. The clinical behavior of RCC is often unpredictable, and less is known about its etiology and risk factors than for most other human cancers.

The aim was to analyze clinicopathological risk factors of RCC in all patients that had been diagnosed with RCC in Iceland between 1971 and 2000, including assessment of early results of nephrectomy for RCC. An additional aim was to analyze the genetic contribution of RCC in the Icelandic population and the effect of incidental detection on survival.

Clinical information was gained from patient charts, their disease was staged according to degree of spread, and the histology was reviewed. Both overall survival and disease-specific survival were analyzed and prognostic factors were evaluated in a multi-variate analysis. For assessment of inheritance, an extended genealogy database was used and relative risks and kinship coefficients were calculated.

It was concluded that stage is the most important prognostic factor of survival for RCC, with nuclear grade adding to the prognostic information about stage. Advanced age of the patient and early calendar year of diagnosis are negative prognostic factors of survival. However, after correcting for grade and especially stage, the histological subtype, tumor size and venous thrombosis lost their significance as independent prognostic factors. Incidental detection increased more than threefold during the study period, with 37% of patients being diagnosed by coincidence after 1995, mostly due to increased use of abdominal imaging for unrelated disease. The increase was most prominent after 1990 and resulted in a significantly improved survival in the last decade of the study. A similar increase after 1990 was seen regarding both incidental detection and survival for both sexes together, with a stable mortality rate. However, increased incidence was only seen in males, indicating that factors other than increase in incidental detection could be involved in improving survival, at least for women. On the other hand, incidental detection was not found to be an independent prognostic factor of survival, which suggests that incidentally-detected RCCs have a similar biological behavior to symptomatic RCCs, but are only detected earlier. Familial aggregation analysis suggested that there is a significant genetic contribution in the majority of sporadic RCCs in Iceland, both for members of the extended family of an affected individual and for close family members. Operative mortality after nephrectomy for RCC has remained low for three decades, and is most often caused by perioperative bleeding and infections. Oncocytomas account for 5.5% of the total number of RCCs in Iceland and, in contrast to the latter, behave clinically as benign kidney tumors.

The fact that every third patient has metastasis at diagnosis affects the prognosis for the whole group of RCC patients, with almost every other patient dying out of the disease within five years from diagnosis (57% 5-year disease-specific survival). However, survival of RCC patients is improving in Iceland, demonstrated with increased incidence and stationary mortality. The main reason for this trend is increase in incidental detection, the incidentally diagnosed tumors being smaller and diagnosed at lower stages than symptomatic RCCs.

Jón Gunnlaugur Jónasson, dósent og yfirlæknir Krabba­meinsskrár KÍ og prófessor Börje Ljungberg frá Umeå-háskólanum í Svíþjóð ásamt doktorsefninu.

Forsíða ritgerðarinnar.

Tómas Guðbjartsson útskýrir efnivið sinn við doktors­vörnina í hátíðarsal Háskóla Íslands.