Abnormalities of the urinary system have been noted on 15% of bone scans (4). Of those, 80% are caused by malignant process such as primary tumor or metastases. Thus, the importance of such observations cannot be over-emphasized. In our case, the incidental bone scan finding was the displacement of the urinary bladder by an ovarian tumor. This does not appear to be a chance occurrence.
Patients with breast carcinoma have been reported to be more prone than those in the general population to develop carcinoma in other organs, specifically, the ovaries and the GI tract. Some investigators believe that endocrine hormones are implicated in the pathogenesis of breast cancer and it seems reasonable to suggest that other organs such as the ovaries, which are under hormonal influence might, therefore, be at risk for malignant conversion. Although the role of hormones is not very well understood in the etiology of breast cancer, the higher incidence of this tumor in premenopausal women is suggestive of estrogenic role in the process (5).
On the other hand, the familial association of breast and ovarian carcinoma has been reported to result from the affect of mothers transmitting a "cancer predisposing gene" to half their daughters (6). Supporting this is the review of Prior and Waterhouse (5) which examined 17,756 registrations for breast and 3,470 for ovarian cancer. An increased risk of a second primary tumor in the ovary was observed in patients diagnosed with a first primary in the breast before 45 years of age (expected (E) = 1.83, observed (O) = 8, P < 0.01). Of interest, no increased risk was found in patients diagnosed after 45 years of age. Analysis of the data also showed that the development of a primary tumor at either site before 45 years of age carried a 2.8 fold increase in risk of a second primary at the other site, (E = 3.21, O = 9, P < 0.01).
Additionally, women who successfully recover from breast, uterine or ovarian cancer have about twice the expected risk of developing colorectal cancer (7). For the patients of the largest group, breast carcinoma survivors, the risk adjusted to family history of GI cancer is 3 (P < 0.003) as compared to control group which was 1. Therefore, continued screening of these patients is valuable in early detection of second primary tumors.
In summary, extraosseous findings on bone scans represent a malignant etiology in 65% of cases (1). The urinary tract is a major non-skeletal component of the bone scan since 45-50% of the radiopharmaceutical is excreted by the kidneys. In patients with breast cancer, by far one of the largest groups routinely images for bone metastases, an awareness of the propensity for developing a second pelvic abdominal malignancy should alert the nuclear medicine physician to attach special significance to the observation of alterations in normal urinary anatomy and function.
2) Rosenthal D, et al. Uptake of bone imaging agents by diffuse pulmonary metastatic calcification. AJR 1979; 129:871-874.
3) Tumeh SS, et al. Uptake of Tc-99m MDP by pseudomyxoma peritonei: a case report. Eur J Nucl Med 1983; 8:364-366.
4) Maher FT. Evaluation of renal and urinary tract abnormalities noted on scintiscans. Mayo Clinic Proc 1975; 50:370-378.
5) Prior and Waterhouse. Multiple primary cancers of the breast and ovary. Br J Cancer 1981; 44:628-636.
6) Lynch, et al. Familial association of breast/ovarian carcinoma. Cancer 1978; 41:1543-1549.
7) Rozen, et al. Colorectal tumor screening in women with a past history of breast, uterine or ovarian malignancies. Cancer 1986; 57:1235-1239.
J. Anthony Parker, MD PhD, firstname.lastname@example.org