Rosen's Breast Pathology, 4e

393

Ductal Carcinoma In Situ

DCIS are negative for high molecular weight cytokeratin, even in epithelia that show marked cautery effect. 334 In 1999, the DCIS “Consensus Conference” proposed a 10-mm margin as the limit of oncologic safety. 187 Ten years later, there was “consensus” among experts at St. Gallen on avoiding the need to insist on a large (e.g., 1 cm) free mar- gin. 335 In the interim years, various progressively lesser ex- tents of optimal clearance were proposed, that is, 3, 2 to 3, 2, and 1 mm. 336–339 Although the need for negative margins has been assimilated in various guidelines for DCIS manage- ment, the absolute need for the attainment of a widely nega- tive margin has been questioned on the basis of the NSABP B1 and B24 trials that only required margins of tumor not touching ink. In this study, only 72 (2.8%) of 2,612 patients treated with breast conservation with and without radiation therapy died of breast carcinoma after 15 years of follow- up. 340 In 2012, Morrow et al. 341 concluded that “bigger is not better” and suggested that a margin with no tumor at the inked surface was satisfactory. This approach places reliance on postsurgical adjuvant radiation and tamoxifen therapy. Given such fluidity, and divergence, of recommendations in the recent past, it would behoove pathologists to report the pathologic findings in an objective manner, that is, re- port the presence of tumor at ink as “positive,” and the clos- est distances of tumor to various margins. The use of vague terms (such as “abutting,” “near,” “approximating,” and “free”), without further elaboration, should be avoided. Innovative approaches such as placement of radioactive “seeds” to enhance tumor localization and thereby ensure adequate margin clearance, 342,343 as well as the intraoperative assessment of surgical margins by the use of radiofrequency spectroscopy during breast-conserving surgery of DCIS, 344 show early promise. Until the last quarter of the 20th century, the standard treat- ment for DCIS was mastectomy. Prior to the introduction of modified mastectomy procedures, the operation was a clas- sical radical mastectomy. Even after the widespread adop- tion of the modified radical mastectomy, an en bloc axillary dissection was routinely performed, yielding ALN metasta- ses in only isolated instances. 18,19,73,74 These operations en- sured at least a 99% cure rate. 19,73,74,309 Systemic recurrences that occurred in 1% or less of patients after such treatment resulted from contralateral carcinomas or foci of invasion that were undetected. 72,73,345,346 The operation was deemed justified because of the very low local recurrence rate and the presence of unsuspected frankly invasive foci discovered in the mastectomy specimens from about 5% of breasts that had only DCIS in the biopsy specimen. 81,347 Mastectomy remains a treatment option for patients with DCIS, but it is infrequently indicated under circumstances outlined by a Consensus Conference on the Treatment of In Situ Ductal Carcinoma (DCIS). 246 The situations in which mastectomy was recommended were as follows: TREATMENT AND PROGNOSIS Mastectomy

1. “Large areas of DCIS of a size that the lesion cannot be removed by an oncologically acceptable excision . . . while still conserving a cosmetically acceptable breast.” 2. “Patients with multiple areas of DCIS in the same breast that cannot be encompassed through a single incision.” 3. “Patients who cannot undergo radiation therapy be- cause of other medical problems, such as collagen vas- cular diseases, or prior therapeutic radiation to the chest for another illness, and for whom treatment by excision alone is not appropriate.” Local recurrence on the chest wall is an unusual com- plication in the treatment of DCIS by total mastectomy. A meta-analysis of published studies reported that the fre- quency of local recurrence following mastectomy alone was 1.4% (95% CI, 0.7 to 2.1). 348 The recurrent lesion may consist of DCIS, 349 or it may manifest invasion. 350 Some of these re- currences are accompanied by residual breast parenchyma, which may harbor persistent DCIS. 351 Most published de- scriptions of local recurrence after mastectomy for DCIS do not comment on the presence or absence of breast pa- renchyma associated with the recurrence. It is essential that persistent breast tissue be looked for and mentioned in the report that describes the specimen from the site of any lo- cal recurrence, regardless of whether the primary lesion had been in situ or invasive. Recurrent carcinoma in residual breast tissue constitutes persistence of the original primary tumor or a new primary carcinoma and has a much more favorable prognosis than the more frequent true local recurrence in a mastectomy scar, which is usually a manifestation of systemic metastases. Recurrent carcinoma in persistent breast tissue is adequately treated in most cases by local excision supplemented by ra- diotherapy and/or systemic chemotherapy, depending upon the size of the lesion and whether invasion is present. 72,352 In one report, the 5- and 10-year survival of patients with an in- vasive local recurrence after mastectomy for DCIS was 83% and 63%, respectively. 350 This result supports the conclusion that the chest wall recurrences were a manifestation of per- sistent carcinoma rather than evidence of systemic metasta- ses in a substantial number of these patients. Recurrence in the preserved nipple is a rare complication of nipple-sparing mastectomy for DCIS. In one instance, recurrence as invasive carcinoma occurred 17 years after a subcutaneous mastectomy that was accompanied by irradia- tion of the nipple. 353 Additional examples of recurrence in the preserved nipple after subcutaneous mastectomy were described by Price et al. 354 Another unusual type of recur- rence consisted of two separate foci of invasive carcinoma at subcutaneous drainage sites 8 years after a patient un- derwent a modified mastectomy for DCIS. 351 No mammary parenchyma was seen at the sites of recurrence. It was sug- gested that DCIS cells dislodged at operation persisted at the drain sites and gave rise to recurrent carcinoma. Recurrent DCIS has been detected as a result of the mam- mographic appearance of calcifications in residual breast tissue after total mastectomy and saline implant reconstruc- tion. 349 Helvie et al. 355 reported six patients who developed invasive recurrent invasive carcinoma at the mastectomy site