Diagnostic changes as a reason for the increase in papillary thyroid cancer incidence in Geneva, Switzerland

Objective: Several studies have reported upward incidence trends of papillary thyroid cancer. It is unclear whether these trends reflect a real risk increase, by some attributed to iodine supplementation, or an artificial one, due to increased diagnostic activity or changed histological criteria. This study examines if these artificial factors explain the increased papillary thyroid cancer incidence in the Swiss canton of Geneva. Methods: All thyroid carcinomas (n = 436) recorded between 1970 and 1998 at the Geneva Cancer Registry were considered. European age-adjusted incidence trends were estimated using linear regression analysis. For papillary cancers we evaluated diagnostic modalities and way of presentation (in particular microcarcinoma < 1 cm or silent carcinoma). In addition, we reviewed the histological slides of follicular carcinomas. Results: Papillary thyroid cancer incidence increased significantly from 0.7 to 1.8/100,000 for men and from 3.1 to 4.3/100,000 for women between 1970-74 and 1995-98. The proportion of microcarcinomas and silent carcinomas increased from 17% to 24% between 1970-79 and 1990-98. At histological review, follicular cancers were more often reclassified as papillary cancer for cases diagnosed between 1970 and 1979 than for cases diagnosed between 1990 and 1998 (45% vs 25%, p = n.s.). Conclusions: The increasing papillary thyroid cancer incidence seems mainly due to changes in histological diagnostic criteria and, to a lesser extent, to increased diagnostic activity. If confirmed, the results of this study indicate that fears of increasing incidence rates of papillary thyroid cancer should not prevent implementation of adequate programs of iodine supplementation in the many areas where iodine deficiency still prevail

Breast-conserving surgery has equivalent effect as mastectomy on stage I breast cancer prognosis only when followed by radiotherapy.

BACKGROUND AND PURPOSE:Early-stage breast cancer is increasing and consequently the use of breast-conserving surgery (BCS). We examined the effect of mastectomy and BCS on overall and breast cancer survival in routine health care in Geneva, Switzerland.PATIENTS AND METHODS:We included all stage I breast cancers treated by surgery (n=1046) recorded at the Geneva Cancer Registry between 1988 and 1999. The effect of treatment type was evaluated by Cox models, which accounted for confounders.RESULTS:Overall, 780 (75%) women had BCS with radiotherapy, 57 (5%) BCS alone and 209 (20%) mastectomy. The overall 10-year survival was 86, 56, and 72%, respectively. The effect of BCS with radiotherapy was similar to that of mastectomy for both breast cancer mortality (adjusted hazard ratio (HR), 0.67; 95%CI, 0.31-1.38) and other causes of mortality (HR, 0.79; 95%CI, 0.49-1.28). Women with BCS alone had higher mortality from breast cancer (HR, 3.95; 95%CI, 1.59-9.84).CONCLUSIONS:This retrospective study shows that BCS plus radiotherapy is the predominant treatment in routine practice for stage I breast cancer in Geneva, with the same effect on survival as mastectomy. In this data set the addition of radiotherapy to BCS substantially reduces mortality from breast cancer without increasing other causes of mortality after 10 years of follow-up