Lárus Jónasson

Colon cancer in Iceland—A nationwide comparative study on various pathology parameters with respect to right and left tumor location and patients age

Increasing evidence suggests genetic, biological and demographical difference between right and left colon cancer. Studies have also indicated age differences in the pathology of colon cancer. There is a scarcity of large‐scale studies that closely examine the pathological differences regarding age and tumor location. The aim of our study was to do an extensive comparison of right‐ and left‐ sided colon cancers as well as comparing patients <50 years with older patients. A retrospective, population‐based study was carried out on all patients with colon cancer in Iceland between 1955 and 2004. A total of 2293 cases were analyzed (1148 men, 1145 women). All histopathology material was re‐evaluated. Differences in tumor characteristics between right and left location and younger (<50) and older (≥50) patients was evaluated in particular. Higher TNM‐stage, larger tumors, vessel invasion, mucinous type, high grade and expanding tumor border occurred more frequently in right‐ versus left‐sided lesions while annular and polypoid tumors were more common in left‐sided tumors (p < 0.05). Young patients had more frequent lymph node metastases, vessel invasion, nonpolypoid lesions and infiltrating tumor border (p < 0.05). Right‐sided lesions show more aggressive features, reflected in morphology and stage. Younger patients present more frequently with adverse features than do older patients. Frequency of right‐ and left‐sided colon cancer differs by age with pronounced age‐location differences in females. This supports the assumption of differences in etiology and carcinogenesis of right‐ and left‐sided colon cancer, and between young and old patients.

pT4 stage II and III colon cancers carry the worst prognosis in a nationwide survival analysis. Shepherd's local peritoneal involvement revisited

The aim of this study is to clarify the prognostic importance of several well‐known but still debated pathological variables related to the survival of colon cancer patients. The study focuses on the definition and survival carried by the pT4 category and stage II where the presence of high‐risk variables may determine whether or not adjuvant chemotherapy is administered. A retrospective nationwide study was carried out including all colon cancer patients that underwent resection in Iceland between 1990 and 2004 (n = 889). All histopathology was reassessed. Cancer‐specific survival (CSS) and overall survival were analysed using Kaplan‐Meier and Cox regression analysis. In stage II, the five‐year CSS for pT4 was 50% (95% CI, 32–69%), which was the lowest survival observed in that stage. In stage III the five‐year CSS was 30% (95% CI, 18–41%) and 37% (95% CI, 26–48%) for pT4 and pN2 tumors, respectively. Lymphatic invasion and differentiation had no prognostic value in stage II. The survival associated with pT4a versus pT4b depends on how these categories are defined with regard to Shepherds local peritoneal involvement (LPI). In the present series, pT4 is a major indicator of poor prognosis in patients with stage II and III colon carcinoma. Four‐tiered TNM or Dukes staging systems are insufficient by not taking this variable into account. Only Shepherds LPI4 and a subgroup of LPI3 (i.e., borderline LPI3/LPI4) should qualify for the pT4a subcategory. The results do not support lymphatic invasion or poor differentiation as high‐risk stage II variables.

Gastric carcinoma : correlation of diagnosis based on biopsies and resection specimens with reference to the Laurén classification

Gastric carcinomas in 382 patients were studied histologically and the results from the preoperative endoscopic biopsies were compared with those from the resected specimens. Using the Lauren classification an overall histological diagnostic agreement between the two specimens was reached in 317 cases, or 83%. The highest diagnostic agreement, 87%, was for intestinal carcinomas. For diffuse carcinomas the diagnostic agreement was 75%. The disagreement in intestinal carcinomas was mainly due to foci of undifferentiated cells and/or signet‐ring cells predominating in the biopsy. The disagreement in diffuse carcinomas was mainly because glandular structures were present at the surface in some of the cases and therefore led to an erroneous diagnosis of intestinal carcinoma. In conclusion, the intestinal type of gastric carcinoma can in most cases be diagnosed correctly from an endoscopic biopsy, whereas the diagnosis of a diffuse carcinoma is less accurate until the resected specimen is available for histological study.

Why is colon cancer survival improving by time? A nationwide survival analysis spanning 35 years

There is limited information present to explain temporal improvements in colon cancer survival. This nationwide study investigates the temporal changes in survival over a 35‐year period (1970–2004) in Iceland and uses incidence, mortality, surgery rate, stage distribution, lymph node yield, tumor location and histological type to find explanations for these changes. Patients diagnosed with colon cancer in Iceland 1970–2004 were identified (n = 1962). All histopathology was reassessed. Proportions, age‐standardized incidence and mortality, relative, cancer‐specific and overall survival and conditional survival were calculated. When comparing first and last diagnostic periods (1970–1978 and 1997–2004), 5‐year relative survival improved by 12% for men and 9% for women. At the same time surgery rate increased by 12% and the proportion of stage I increased by 9%. Stage‐stratified, improved 5‐year relative survival was mainly observed in stages II and III and coincided with higher lymph node yields, proportional reduction of stage II cancers and proportional increase of stage III cancers, indicating stage migration between these stages. Improvement in 1‐year survival was mainly observed in stages III and IV. Five‐year survival improvement for patients living beyond 1 year was minimum to none. There were no changes in histology that coincided with neither increased incidence nor possibly influencing improved survival. Concluding, as a novel finding, 1‐year mortality, which previously has been identified as an important variable in explaining international survival differences, is in this study identified as also being important in explaining temporal improvements in colon cancer survival in Iceland.