Page 40 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

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Chapter 2
A second recurrence risk factor we found was age. Mean age at primary SGPA diagnosis was 49 in patients who did not develop a recurrence later on, and 40 in patients who did. Although there may be an age bias here (higher age suggesting shorter survival, with death as a competing event), our findings are in line with literature [33,37–39]. Some researchers have explained the age difference by suggesting that surgeons tend to take a less radical approach and make smaller incisions in younger patients, for esthetical reasons [36]. Our multivariate analysis, however, did not show any correlation between age and margin status. Wittekindt et al. observed a further age difference. In their study population, mean age at primary diagnosis turned out to be lower in single-recurrence patients than in multiple-recurrence patients (30.2 versus 40.3) [36]. Possibly, tumor biology is somehow different in younger patients, because of hormonal aspects, genetic background, or some other factor as yet unknown.
A third risk factor for recurrence in our cohort was tumor location, which to our knowledge is a novel finding. SGPA in minor salivary glands was found to recur less frequently than SGPA in larger glands. Lumps in the minor glands are possibly more likely to be noted at an earlier stage. Moreover, complete excision of these lumps is easier to achieve, although margin status may be hard to assess for lack of capsule formation [40].
Female gender was not found to be a recurrence risk factor, which is in line with Maran et al. [41] in smaller series, but in contrast to other publications [36,42,43].
Limitations: There are some limitations to our study. First, there is a slight information bias. Given the suboptimal diagnostic accuracy of cytology (84- 99%)% [44], we included histology-confirmed SGPA, only. With only 98 cytology diagnoses, however, and no data on non-pathology-proven recurrences, the 4.6% recurrence rate we found may be something of an underestimate, although hardly a gross one.
A second limitation is the lack of radiotherapy data, because literature suggests there is a role for radiotherapy in the adjuvant treatment of recurrent SGPA.