Mammographic Diagnosis of Breast Carcinoma : An Institutional Experience

Mammogram is a common diagnostic modality for breast carcinoma. Diagnostic mammogram is available at only few centers in Nepal. The aim of this study was to determine the accuracy of diagnostic mammogram in Nepalese women suffering from breast carcinoma. A retrospective analysis of the breast carcinoma was carried out in the Department of Surgery, Tribhuwan University Teaching Hospital from October 1995 to October 2007. Out of 556 patients with histologically proven breast carcinoma, 378 patients (68%) had undergone mammography. Breast carcinoma was identified on mammography in 328 (87%) cases while 50 cases (13%) were reported as normal or benign lesions. Diagnostic mammogram had a sensitivity of 86.8%, a specificity of 98.6% with a positive predictive value of 68.8% and a negative predictive value of 99.5%. In mammographically missed breast carcinoma, 34% were less than 40 years of age (P<0.05), 60% were premenopausal (P<0.05) and 88% patients presented with a painless lump. The study shows that the diagnostic accuracy of the mammogram is very high. However, there is a chance of missing the breast carcinoma in young and premenopausal women.


IntroductIon
Diagnostic mammogram is commonly used to facilitate the diagnosis of breast cancers in women who present with symptoms or signs of the disease.The symptoms or signs may include a breast lump, pain, nipple discharge or retraction, and breast dimpling or other skin changes.A diagnostic mammographic examination usually consists of standard screening views and additional views using spot compression and/or magnification of a specific area.Although mammography is sufficient to evaluate the clinical finding, additional imaging with ultrasound, ductography or other imaging techniques may also be required.
2][3] Diagnostic mammogram may have superior performance over screening mammogram, because noticeable symptoms or clinical findings may indicate a more advanced tumor that is easier to locate and identify.Dee and Sickles found that tumors detected by diagnostic mammogram were larger than those detected by screening mammogram. 4 a country data published by WHO (1998), lung cancer accounted for 8.2% of all cancer cases, while cancer of the cervix accounted for 6.3% and breast cancer for 6% of all cancer cases in Nepal. 5
To clarify the factors for the mammographically missed 13% of breast carcinoma, the characteristics of 378 operated and histopathologically proven cases of carcinoma breast were analyzed.Individual patient factors like age, symptoms, menopausal status, size of breast lump, clinical stage and hormone receptor status were analyzed.The comparison between mammographically malignant and benign characteristics of women with histologically proven breast carcinoma has also been shown (Table 3).
In the mammographically malignant group, 19% of patients were between 20 to 39 years of age whereas in the mammographically benign group, 34% of the patients were in this age group, which was statistically significant (Table 3).The average age was 48.7 (range 22 -82) years in mammographic malignant group and 43.3 (range 22 -67) years in the mammographically benign group.
Ninety-six percent of patients in both groups presented with lump, the mean duration of which was 8 months (range two weeks to 2.9 years) in the mammographically malignant group and 9 months (range two weeks to two years) in the mammographically benign group.Sixty percent of patients were premenopausal in whom breast carcinoma was missed mammographically, whereas only 40% of patients were premenopausal in mammographically malignant cases (P<0.05)(Table 3).
In the mammographically benign group, 34% of patients had a tumor size of more than 5 cm whereas it was 28% in the mammographically malignant group.In both the groups, more than 80% of breast carcinoma was in stage II/III ( This study assessed the overall performance of diagnostic mammography.][8] Duijm et al found that diagnostic mammography had a sensitivity of 92.0% and a specificity of 97.7%.Eltahir et al. [6][7] obtained similar results of 93.2% sensitivity and 96.7% specificity for symptomatic women.In a study by Flobbe et al. 8 diagnostic mammography had a sensitivity of 89% and a specificity of 98%.Our results are comparable to the above studies.A metaanalysis of screening studies showed that sensitivity ranged from 83% to 95% and specificity ranged from 93.5% to 99.1%. 3Screening sensitivity may be lower because the cancers detected are smaller than those detected with diagnostic mammography.However, the population undergoing screening is older, and average breast density may be less.0][11][12] We found similar results with diagnostic mammography.
A significant number of patients with breast carcinoma in the younger and premenopausal group were missed by diagnostic mammogram.This may be attributed to dense breast tissue.In younger patients with dense breast, additional imaging with ultrasonography is helpful.The diagnostic accuracy for carcinomas of the breast appears to improve when mammography is combined with ultrasonogram even in cases that reveal no evidence of microcalcification or other abnormalities 13 .However, in our study, all patients were evaluated by mammography not in combination with ultrasound.Symptoms, size of lump and stage of carcinoma were not significant in our study.
Our previous study showed ER/PR positivity rate ranging from 11 to 15%, but in the present study it was 38.9%. 14This could be due to the less number of cases in the previous study.
Sidharth et al.Diagnostic Mammogram in Breast Carcinomacarcinoma is one of the most common carcinoma in females, the role of mammogram has not been studied in Nepal.We evaluated the performance of diagnostic mammogram and how performance would be influenced by the characteristics of the women undergoing the diagnostic investigation.
Even though breast Downloaded from www.jnma.com.npJNMA Discussion Forum www.xenomed.com/forums/jnmaThe individual patient factors like age, symptoms, menopausal status, size of breast lump, clinical stage and hormone receptor status were retrieved for analysis.The primary performance outcomes like sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of mammogram were analyzed.Statistical analysis was done by using chi-square test for variables, P<0.05 being considered as statistically significant.

table 3 . characteristics of women with histologically proven breast carcinoma who underwent ammography
Sidharth et al.Diagnostic Mammogram in Breast Carcinoma Downloaded from www.jnma.com.npJNMA Discussion Forum www.xenomed.com/forums/jnma