Implants and Breast Cancer Screening
Physical examination of an implanted breast should include a traditional breast evaluation, with the possible additional assessment of capsular contracture, if present, using the Baker system of classification.13,16,38 Cady et al., McCool et al., Barton et al., and Pennypacker et al. include detailed instructions in their articles on how to perform a thorough breast examination on a non-augmented breast. An example of an examination technique is the MammaCare® method described by Barton et al. and Penny-packer et al. Easily remembered for its theme of the number 3, MammaCare® advises the use of a vertical strip pattern to cover all the breast tissue, making circular motions with the pads of the middle three fingers, and applying three different levels of pressure to each area being palpated. Three minutes or more should be spent on each breast.
If capsular contracture is evident, the degree to which this complication has progressed can be graded by Baker's classification scale, as depicted in Table 2 . As mentioned previously, significant contracture usually requires additional surgery to remove capsule tissue or the implant itself with possible implant replacement.
The effect of mammary prostheses on the sensitivity and specificity of BSE and CBE has been sorely lacking. Eklund and Cardenosa state that the presence of an implant does not compromise physical assessment of the breast and that, in fact, it facilitates it. The smooth anterior surface of the implant can be used as a backdrop (especially if it is in the subglandular position), and the thinning of the breast tissue over the implant heightens palpation sensitivity. In a 1993 retrospective, cohort-controlled study comparing 33 augmented patients with 1,735 non-augmented patients, Clark et al. found that not only did BSE and CBE detect more cancers than mammography (70% versus 58%), but also the tumors were smaller and there was a lower incidence of axillary metastasis compared with the control group (22% versus 58%). Although the data could suggest that physical examination is more sensitive in the augmented breast, the authors point out that there may be other contributing factors among this population, such as an increased body awareness and practice of BSE, the use of breast massage in an effort to prevent capsular contracture, and/or the enhanced postsurgical interaction with their surgeons that typically entail physical evaluation.
Given that the success of physical examination of the implanted breasts in the above study was due to improved sensitivity, clinical evaluation can still be challenging. There are numerous similarities between the physical presentation of breast cancer and the physical characteristics of implants and implant complications. For example, breast asymmetry can be due to tumor formation, capsular contracture,[5,14] silicone gel bleed or rupture, or saline leakage or deflation. Breast lumps or nodules may be malignancy, an implant valve, periprosthetic calcifications, or silicone gel from a ruptured implant. Axillary adenopathy could be invasive cancer or free silicone that has migrated into nodal tissue. Finally, wrinkling or rippling of the skin may be the "orange peel" sign associated with cancer or a consequence of subglandular placement of an implant.[5,13] Most likely, the ability to correctly differentiate the true cause in the previous scenarios comes with experience, and practitioners not familiar with augmented breasts should refer abnormal findings to a plastic surgeon.
There is widespread recognition that the presence of breast implants increases the difficulty in the performance of mammography as well as the interpretation of mammo-graphic films. There are multiple mechanisms by which this occurs, the first being that all implants appear radiopaque on film, albeit to varying degrees.[42,43,44] Several studies have calculated the amount of parenchymal tissue obscured by an implant to be between 22% and 83%.[25,45,46] In addition to the opacity of the implant, breast tissue that is displaced and condensed by the prosthesis hinders the detection of small cancers, which include microcalcifications, architectural distortions, and occult masses.[16,41] Implants are less compliant than breast tissue, thus achieving the level of compression required during mammography for optimal visualization of the parenchyma is nearly impossible.[42,43,44] Finally, the production of implant-related artifact that appears on film can confuse its interpretation with carcinoma. Periprosthetic calcifications and scarring of breast parenchyma can mimic the presentation of cancer.
To increase the amount of breast tissue imaged and to improve clarity without risking the integrity of the implant, Eklund and colleagues[43,44] developed certain displacement and compression techniques specific for women with breast prostheses. Intended to supplement the standard craniocaudal (CC) and mediolateral oblique (MLO) views, the modified techniques involve two additional CC and MLO views, plus an optional fifth 90° lateral view, in which the implant is pushed back against the chest wall and the breast tissue pulled forward. With the implant displaced posteriorly, compression can then be applied to the tissue anterior to the implant. Although the Eklund views enhance imaging of the tissue in front of the prosthesis, standard views provide better imaging of breast tissue behind and under-neath the implant, as well as the lower axillary area. With the Eklund method, women with implants experience longer examination times, increased exposure to radiation, and an increased risk of implant rupture.[5,43] Because of the complicated nature of mammographic evaluation of these women, the American Society of Reconstructive and Plastic Surgery and the FDA encourage providers to refer patients with breast implants to skilled mammographers experienced with the Eklund views.
The quantity and quality of breast tissue imaged around implants in the standard and Eklund views depend on a number of factors. Breast size, glandularity, and fat content, as well as implant size, position, and associated complications all affect mammographic success.[16,42] Of these, implant position and capsular contracture have the greatest effect. Submuscular implantation affords nearly twice the amount of breast tissue visualized compared with that of subglandular augmentation, and severe encapsulation (Baker grade 3 or 4), which does not permit implant displacement, has been reported to reduce visualized areas by up to 50%. Eklund and Cardenosa recommend using the fifth modified view whenever capsular contracture is evident.
The extent to which the Eklund views enhance mammography has been disputed. In their initial publication describing their modified techniques, Eklund et al. estimated that the use of these techniques improved mammo-graphic evaluation in 92% of patients. However, subsequent data by Handel et al. showed that the displacement views increased the area visualized above that obtained by standard compression by less than 5%. Similarly, Silver-stein et al. found that even with the Eklund technique, 39% of breast tissue in subglandular implants and 9% in subpectoral implants remained obscured. Eklund and Cardenosa eventually responded to these reports with the statement that their calculations were flawed and that an accurate method that quantifies the amount of tissue imaged in an augmented breast is not available. On review of this data, in 1991 the American College of Radiology stated that adequate mammographic examination of women with breast augmentation is possible. Imaging an augmented breast frequently requires tailored supplemental implant displacement views, or ancillary studies such as ultrasonography, to achieve optimal visualization of breast tissue.
Besides altering mammographic practice, experimental work with new substances to fill breast implants is being conducted in hope of circumventing some of the identified adverse effects on mammography. As mentioned previously, oil-filled implants are being evaluated for potential use due to their organic constitution and radiolucency on film. Garcia-Tutor et al. assessed whether triglyceride-filled implants allow mammographic visualization of benign and malignant lesions in mastectomy specimens. They found that although the implant did not interfere with the imaging of microscopic and macroscopic calcifications, the implants required a higher kilovoltage and milliamperage compared with the specimens alone. Thus, exposure to increased levels of radiation would be necessary to thoroughly evaluate a breast with an oil-filled implant. More research on the use of oil and other materials as alternatives to saline is needed.
J Midwifery Womens Health. 2003;48(5) © 2003 Elsevier Science, Inc.
Cite this: Breast Implants and Breast Cancer Screening - Medscape - Oct 01, 2003.