Follicular thyroid carcinoma with capsular invasion alone: a nonthreatening malignancy.
BACKGROUND
The study was designed to determine whether invasion of the tumor capsule, in the absence of vascular invasion (VI), was significant in predicting cause-specific mortality in follicular thyroid carcinoma (FTC).


METHODS
Seventy-two patients with FTC were treated by us during 1971 through 1985. In 65 cases the tumors could be classified as either showing capsular invasion (CI) alone (20) or VI, with or without CI, (45). Median follow-up of 45 survivors was 11 years; 12 patients died of FTC.


RESULTS
The 10-year occurrence rates for cause-specific mortality and distant metastases were 28% and 19%, respectively, for patients with VI. Comparable rates for the patients with CI were 0% (p = 0.019) and 0% (p = 0.052), respectively. By univariate analysis, higher rates of cause-specific mortality were significantly associated with distant metastases at diagnosis (p < 0.0001), the presence of VI (p = 0.019), and moderate or marked microinvasion (p = 0.019). In stepwise multivariate analyses, only distant metastases at diagnosis had independent prognostic significance (p < 0.0001) in the prediction of cause-specific mortality. In a Cox model, adjusting for distant metastases at diagnosis, the presence of VI was of borderline significance (p = 0.06) in predicting cause-specific mortality.


CONCLUSIONS
FTC, diagnosed on the basis of CI alone, did not result in either distant metastases or cancer-related death. The dominant determinant of cause-specific mortality was the presence of distant metastases at diagnosis.
van Heerden
J A
JA
Department of Surgery, Mayo Clinic, Rochester, MN 55905.
Hay
I D
ID
Goellner
J R
JR
Salomao
D
D
Ebersold
J R
JR
Bergstralh
E J
EJ
Grant
C S
CS
D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D011184:Postoperative Period; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome