Continuous Rural-Urban Coding for Cancer Disparity Studies: Is It Appropriate for Statistical Analysis?

Background: The dichotomization or categorization of rural-urban codes, as nominal variables, is a prevailing paradigm in cancer disparity studies. The paradigm represents continuous rural-urban transition as discrete groups, which results in a loss of ordering information and landscape continuum, and thus may contribute to mixed findings in the literature. Few studies have examined the validity of using rural-urban codes as continuous variables in the same analysis. Methods: We geocoded cancer cases in north central Florida between 2005 and 2010 collected by Florida Cancer Data System. Using a linear hierarchical model, we regressed the occurrence of late stage cancer (including breast, colorectal, hematological, lung, and prostate cancer) on the rural-urban codes as continuous variables. To validate, the results were compared to those from using a truly continuous rurality data of the same study region. Results: In term of associations with late-stage cancer risk, the regression analysis showed that the use of rural-urban codes as continuous variables produces consistent outcomes with those from the truly continuous rurality for all types of cancer. Particularly, the rural-urban codes at the census tract level yield the closest estimation and are recommended to use when the continuous rurality data is not available. Conclusions: Methodologically, it is valid to treat rural-urban codes directly as continuous variables in cancer studies, in addition to converting them into categories. This proposed continuous-variable method offers researchers more flexibility in their choice of analytic methods and preserves the information in the ordering. It can better inform how cancer risk varies, degree by degree, over a finer spectrum of rural-urban landscape.

Histological characteristics and altered expression of interleukins (IL) IL-13 and IL-15 in endometria of levonorgestrel users with different uterine bleeding patterns.

OBJECTIVE: To determine the relationship between uterine bleeding patterns in levonorgestrel users with endometrial histology and expression of interleukins (IL) IL-13 and IL-15. DESIGN: Prospective observational study. SETTING: Academic research center. PATIENT(S): Questionnaires were sent to patients (n = 578) who had levonorgestrel implants concerning bleeding patterns; 35 of these patients were identified to have regular cycle (n = 13), amenorrhea (n = 8), or metrorrhagia (n = 14). INTERVENTION(S): Endometrial biopsies, serum, histology, and immunostaining. MAIN OUTCOME MEASURE(S): Endometrial histological assessment and immunostaining for IL-13 and IL-15 and for blood levonorgestrel, E2, and progesterone levels by ELISA or RIA. RESULT(S): No correlation was found between circulating levonorgestrel, E2, or progesterone levels with the bleeding patterns, although a trend toward a lower E2 level was observed in patients with amenorrhea who had inactive endometrium. There was a direct correlation between bleeding patterns and endometrial histology, as well as IL-13 and IL-15 expression in patients with regular cycles and metrorrhagia, demonstrating secretory and proliferative endometrium, respectively. Some patients in each group were also identified as demonstrating endometritis. CONCLUSION(S): Endometrial histology may assist directing therapy and subsequently increasing compliance in progestin-only contraceptive users with irregular bleeding who fail to respond to standard therapies. Altered endometrial expression of IL-13 and IL-15, key cytokines in inflammatory and immune cell trafficking, may influence events, leading to irregular bleeding.

Malignant melanoma associated with lichen sclerosus in the vulva of a 10-year-old.

Malignant melanoma of the vulva in childhood is a rare neoplasm. Lichen sclerosus of the vulva in childhood is also a rare disease. The association of these two rare lesions in the vulva of young girls is extremely rare. We present a 10-year-old white girl with malignant melanoma associated with lichen sclerosus of the vulva. She had dark pigmentation of both the labia minora and posterior fourchette. The inner labia majora and fourchette showed whitish, glistening areas of skin. Histologic examination found mostly an in situ lentiginous/mucosal melanoma with focal invasion to a depth of 0.44 mm in the left upper labium majus. All specimens showed evidence of lichen sclerosus. Partial vulvectomy was performed, and no metastases were detected at the time of treatment. The patient has been disease free for the 12 months after treatment. It is critical for physicians to realize that melanoma can occur in children, and although rare, can occur in the vulva. We feel that lichen sclerosus in this instance may represent a pattern of host immune response to melanoma.