# Radiation Oncology/Breast/Benign

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* NSABP trials
Relative Risk of Developing BCA (PMID 16034013) :
| Risk | Proliferation | Histology | Specific Findings |
| No increase | Nonproliferative/ minimal (67%) | Fibrocystic changes | Cysts & ductal ectasia, mild hyperplasia, nonsclerosis adenosis, periductal fibrosis, simple fibroadenoma |
| No increase | Nonproliferative/ minimal (67%) | Benign tumors | Hamartoma, lipoma, phyllodes tumor (some have malignant features), solitary papilloma, neurofibroma, giant adenoma, adenomyoepithelioma |
| No increase | Nonproliferative/ minimal (67%) | Traumatic lesions | Hematoma, fat necrosis, foreign body penetration |
| No increase | Nonproliferative/ minimal (67%) | Infections | Granuloma, mastitis |
| No increase | Nonproliferative/ minimal (67%) | Sarcoidosis | |
| No increase | Nonproliferative/ minimal (67%) | Metaplasia | Squamous, apocrine |
| No increase | Nonproliferative/ minimal (67%) | Diabetic mastopathy | |
| Small increase (RR 1.5-2.0) | Proliferative, no atypia (30%) | Usual ductal hyperplasia, complex fibroadenoma, papilloma/papillomatosis, radial scar, blunt duct adenosis | Usual ductal hyperplasia, complex fibroadenoma, papilloma/papillomatosis, radial scar, blunt duct adenosis |
| Moderate increase (RR >2.0) | Proliferative, with atypia (4%) | Atypical ductal hyperplasia, atypical lobular hyperplasia | Atypical ductal hyperplasia, atypical lobular hyperplasia |
By analogy to colon CA, breast lesions may develop in a linear fashion:
* Normal -> Usual ductal hyperplasia -> Atypical ductal hyperplasia -> DCIS -> Invasive CA
* Causal evidence is lacking

## Radial Scar

* Region of central sclerosis, surrounded by epithelial proliferative lesions, cystic changes, and papillomas extending radially from the central sclerosis. If >1.0 cm, can be termed "complex sclerosing lesions"
* On screening mammogram, may be indistinguishable from small invasive CA
* It appears to be pertuberation of normal stroma, but whether it is a precursor lesion is yet to be established
* Associated with invasive/DCIS pathology ~20%, proliferative/ADH pathology ~20%, and benign ~60%
* One study (Nurses Heatlh Study, 1999) found presence of RS to be an independent risk factor for BCA. However, a larger study (Vanderbilt, 2006) found that the risk is largely attributable to co-existent proliferative disease (e.g ADH)
* If there is associated invasive CA, DCIS, or proliferative pathology, it should be managed as such. There is no consensus as yet on how to manage benign solitary radial scar
* Ottawa, 2006 (1995-2003) PMID 16944680 -- "Management of radial scars found at percutaneous breast biopsy." (Becker L, Can Assoc Radiol J. 2006 Apr;57(2):72-8.)
** Retrospective. 184/227 radial scar biopsies done via 14-gauge (144 biopsies) or 11-gauge bx (40 biopsy). 30 lesions 14-gauge followed by 11-gauge
** Presence of RS: associated with CA 20%, high-risk lesion 20%, benign lesion 60%.
** Specificity: 4% CA missed (5% for 14-gauge and 0% for 11-gauge), underestimated in 22% (25% and 17%).
** Conclusion: If benign RS found on 14-gauge, need 11-gauge or surgery. If benign RS found on 11-gauge, mammographic follow up sufficient
* Vanderbilt, 2006 (1950-1986) PMID 16502407 -- "Interdependence of radial scar and proliferative disease with respect to invasive breast carcinoma risk in patients with benign breast biopsies." (Sanders ME, Cancer. 2006 Apr 1;106(7):1453-61.)
** Retrospective. 9556 women (biopsied) enrolled in Nashville Breast Cohort. RS in 9.2% Most found incidentally. Average F/U 20.4 years
** Risk of IBC: RS 7.0% vs. 5.5% controls (RR 1.8 at 10 years, SS). 92% of women with RS had proliferative disease; but RS only present in 1.3% of bx without proliferative disease. Stratifying for proliferative disease resulted in minimally increased risk
** Conclusion: RS mildly elevates risk of IBC, but largely attributable to co-existent proliferative disease. Further interventions should be based on extent of atypical hyperplasia
* Newcastle upon Tyne, 2005 (UK)(1988-2002) PMID 16024215 -- "All radial scars/complex sclerosing lesions seen on breast screening mammograms should be excised." (Fasih T, Eur J Surg Oncol. 2005 Dec;31(10):1125-8.)
** Retrospective. 124 women from screening program, detected by mammogram, with histologically confirmed RS
** Presence of RS: 66% pure radial scar, 18% ADH, 16% DCIS or invasive CA
** Mammogram: If FNA, mammogram 5/9 malignancy; if localization Bx, mammogram 4/11 malignancy
** Conclusion: All screen-detected stellate lesions should be excised due to association with pre-malignant and malignant disease
* Melbourne, 2003 PMID 12518358 -- "Fourteen-gauge needle core biopsy of mammographically evident radial scars: is excision necessary?" (Cawson JN, Cancer. 2003 Jan 15;97(2):345-51.)
** Prospective. 75 consecutive RS detected by mammogram from population-based screening. 55 patients stereotactic core Bx first, 8 patients US-guided core Bx first, followed by excision bx
** Radial scar: overall 51/62 patients (82%). Sensitivity for stereotactic 85%, for US-guided 63%
** Associated lesions: in 4 patients with DCIS on excision, stereotactic bx revealed ADH or DCIS (both of which require excision). No invasiave CA. ADH present in 57%, found on biopsy in 72%
** Conclusion: Stereotactic core bx proven RS can be managed by mammography, provided there is no associated DCIS, ADH, or LCIS
* John Wayne CI, 2002 PMID 12388495 -- "Percutaneous core needle biopsy of radial scars of the breast: when is excision necessary?" (Brenner RJ, AJR Am J Roentgenol. 2002 Nov;179(5):1179-84.)
** Retrospective. 157 lesions treated with surgery (102) or followed by mammography (55)
** CA risk: if ADH present, CA in 28%; if no atypia, CA in 4%.
** Sensitivity: Missed in 9% of spring-loaded vs. 0% of vacuum-assisted (SS); missed in 8% if <12 samples vs. 0% if >=12 samples
** Conclusion: RS diagnosis likely reliable if no ADH, bx includes >=12 specimens, and mammography agrees. If not, then need excisional bx
* Nurses Health Study, 1999 PMID 9971867 -- "Radial scars in benign breast-biopsy specimens and the risk of breast cancer." (Jacobs TW, N Engl J Med 1999 Feb 11;340(6):430-6.)
** Case-control. 1396 women from Nurses' Health Study, 255 women with BCA, 1141 controls. Median F/U 12 years
** Radial scar: 99/1396 women (7.1%); mostly incidental finding (median 4.0 mm)
** Cancer risk: Overall RR 1.8; if proliferative disease without atypia, RR 3.0 if RS vs. RR 1.5 if no RS; if proliferative disease with atypia, RR 5.8 if RS vs. RR 3.8 if no RS
** Conclusion: RS is an independent histologic risk factor for BCA

## Review

* 2005 PMID 16034013 -- "Benign breast disorders." (Santen RJ, N Engl J Med. 2005 Jul 21;353(3):275-85.)