Microinvasive technology for the diagnosis and staging of breast cancer

The purpose of this thesis was to evaluate microinvasive technology for the management of non-palpable mammographic findings with high risk for breast cancer. The specific objectives were, for the first part, to evaluate the Advanced Breast Biopsy Instrumentation System (ABBI) as a diagnostic and therapeutic tool for breast disease. For the second part, the objective was to evaluate lymphoscintigraphy with a malignancy specific radioactive agent (99m Technetium Sestamibi) as a non-surgical staging tool for breast cancer. Design. The thesis consists of two observational studies. The first study was partially retrospective and partially prospective. The second study was prospective. The research was conducted between September 1997 and December 2001. Methods. For the first study 262 women with non-palpable mammographic abnormalities were enrolled. Of these, 260 women underwent an ABBI. The ABBI procedure was performed by 3 surgeons in two hospitals in Montreal. The files of 531 women with similar findings who underwent a wire localization excisional biopsy in the same hospitals by the same surgeons were retrospectively reviewed. Data obtained included technical success, macroscopic and microscopic clarity of margins, need for supplemental surgery and residual cancer, volume of breast tissue excised, patient satisfaction, surgeon volume-performance association and health care costs. For the second study, 110 women with confirmed operable primary breast cancer who required axillary lymph node dissection were enrolled. All the patients underwent two lymphoscintigraphies. The first (preliminary) lymphoscintigraphy took place at least 2 weeks before surgery and the second (preoperative) took place 2-24 hours before surgery. For the preliminary lymphoscintigraphy, 47 (42.7%) of the 110 women were tested with 99mTechnetium Sestamibi and 63 (57.3%) were tested with 99mTechnetium Sulphur Colloid. For the preoperative lymphoscintigraphy all patients were tested with 99mTechnetium Sulphur Colloid. All patients underwent axillary lymph nodes dissection. The data reviewed was the presence of metastasis in the axillary lymph nodes excised and the lymphoscintigraphy gamma camera imaging and gamma probe digital outcomes. The ROC curve was used to define the most probable cut-off points for the distinction between gamma counts representing positive and negative for metastasis axillary lymph nodes. Results. For the first study, diagnostic effectiveness of the ABBI was 99.6% and the mean volume of excised breast tissue was 40cc. No serious complications were reported. For wire localization, the diagnostic effectiveness was 98.0% and the mean volume of excised breast tissue was 102cc. severity of complications was similar between the two techniques. The therapeutic effectiveness of the ABBI was 76.3%, supplementary surgery was required in 27.6% of the patients, and residual cancer was detected in 23.8%. The therapeutic effectiveness of wire localization biopsy was 47.0%, 53% of the patients underwent supplementary surgery and residual tumor was found in 48.0%. Of the 260 patients who underwent an ABBI, 51% reported a good level of satisfaction and 23% reported excellent. A significant association was shown between volume and therapeutic effectiveness for all 3 surgeons. On the average, the ABBI resulted in a cost reduction of $5,352 CAD (2000). For the second study, the sensitivity of 99mTechnetium Sestamibi lymphoscintigraphy imaging was 50%, the negative predictive value was 83.8% and the proportion of false negative results was 17.1%. Logistic regression showed a statistically significant (p<0.001) association between the gamma probe counts and axillary lymph node metastasis. Using 3,080 counts as cut-off point on the ROC curve the sensitivity and false negative rate were 100%, the specificity was 94.3%, and the positive predictive value was 83.3%. Conclusion. The results of the first study show that the ABBI offers a safe and well tolerated microinvasive surgical technique, with superior therapeutic effectiveness, less invasiveness, and better cost effectiveness than wire localization excisional biopsy. The strong volume-performance association shows that the therapeutic effectiveness of the ABBI can improve with proper training and experience. The results of the second study show that 99mTechnetium Sestamibi lymphoscintigraphy imaging was 50% the negative predictive value was 83.8% and the proportion of false negative results was 17.1%. A significant association was shown between the intensity of radioactivity in the hot node as measured by the gamma-probe counts and the presence of axillary lymph node metastasis. In conclusion, this thesis demonstrates that both the ABBI and lymphoscintigraphy with 99mTechnetium Sestamibi are superior to conventional techniques used for the management of mammographic abnormalities and specifically breast cancer. Proper training of surgeons in highly qualified training centers with a high volume of cases can help further improve the effectiveness and increase the practise of these techniques in Canadian hospitals. This may in turn increase the benefits for the patients and reduce the healthcare costs for the management of breast disease and specifically breast cancer in Canada.

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