Epidemiology:
Incidence of Disease:
•most common cancer among women in the US (excluding skin)
•second leading cause of cancer deaths in women⁵
•women in rural areas have lower breast cancer rates than do women in urban areas
•breast cancer is much more common in Western countries than Asian countries
•majority of breast cancer cases are diagnosed in women age 55 and older²
•1% of breast cancers occur in men⁶

Etiology:
Risk & Causative Factors:
•gender is the biggest risk because breast cancer occurs mostly in women
•age - the risk of breast cancer increases with age
•genetics - family history of breast cancer
•hormones - age of menarche, first pregnancy, menopause, use of oral contraceptives
•diet - high dietary fat intake
•lifestyle - overweight or obese
•benign breast disease
•environmental causes - radiation treatment to the upper body before 30 years of age⁶

Signs & Symptoms:
•Most patients with carcinoma in situ, T1 or T2 breast cancers present with a painless or slightly tender breast mass or have an abnormal screening mammogram.
•Approximately 40% to 50% of these lesions are detected by mammography only; approximately 35% of tumors detected by mammography and physical examination are invasive carcinomas smaller than 1cm.¹

Diagnostic Procedures:
Workup includes:
•complete clinical and family history
•physical examination including breasts, axilla, supraclavicular area, abdomen and pelvis
•tests including needle aspiration, biopsy, evaluation for hormone receptors
•imaging before biopsy includes mammography or xeromammograhy, chest radiographs
•imaging after biopsy includes bone scan, liver and spleen scan (if bone scan is positive), internal mammary lymphoscintigraphy (as indicated), skeletal studies
•labs include complete CBC, chemistry (with liver function tests when indicated), urinalysis
•optional tests would be growth factor, DNA index and oncogene assays (BRCA1, BRAC2, her B-2, etc)¹

Histology:
"Infiltrating ductal carcinoma is the most common histologic type of breast malignancy, accounting for 70% of all breast cancers. Infiltrating lobular carcinoma is the next most common type, comprising about 5% to 10% of breast cancers." "There are several other relatively rare types of infiltrating breast cancer, such as mucinous or colloid, tubular, and papillary carcinoma. These lesions have distinct histologic characteristics and tend to yield a more favorable prognosis."⁷
Lymph Node Drainage:
A network of lymphatics lies over the entire surface of the chest, neck and abdomen and become dense under the areola. See image below.²
Breast_Lymph_nodes.jpg

Lymphatic drainage moves superiorly and laterally towards the axillary lymph nodes. See image below of axillary lymph node levels.²
Axillary_lymph_nodes.jpg

Metastatic Spread:
Lymphatic spread is most common, but breast cancer can also spread by direct invasion and by hematogenous spread.² Axillary node metastases are directly related to tumor size and are found in 20 to 40% of newly diagnosed T1 and T2 breast cancers, respectively. Supraclavicular nodes are occasionally involved. Metastasis to the internal mammary nodes tends to occur when the axillary nodes are involved and for inner quadrant and central tumors. Hematogenous metastases can occur to the lungs, pleura, bone, brain, eyes, liver, ovaries, adrenal glands, and pituitary gland.¹,²
Grading:
"Histologic tumor grade (sometimes called the Bloom-Richardson grade, Scarff-Bloom-Richardson grade, or Elston-Ellis grade) is based on the arrangement of cells in relation to each other: wheter they form tubules; how closely they resemble normal breast cells (nuclear grade); and how many of the cancer cells are in the process of dividing (mitotic count). This system of grading is used for invasive cancers but not for in situ cancers.

-Grade 1 (well differentiated) cancer have relatively normal-looking cells that do not appear to be growing rapidly and are arranged in small tubules.
-Grade 2 (moderately differentiated) cancer have features between grades 1 and 3.
-Grade 3 (poorly differentiated) cancers, the highest grade, lack normal features and tend to grow and spread more aggressively."⁴


Staging:
AJCC/TNM (Please see table below)¹,³
Breast_Cancer_Staging_T_rev.jpg
Breast_Cancer_Staging_N_rev.jpg
Breast_Cancer_Staging_M_rev.jpg

Radiation Side Effects:
The most frequent complications associated with conservation surgery and irradiation are arm or breast edema, breast fibrosis, painful mastitis or myositis, pleumonitis, and rib fracture.¹
Prognosis:
​The overall 5-year survival rate regardless of disease status is 85%. The 5-year survival decreases to 77% if evidence exists of regional spread. If there is metastasis present at the time of diagnosis the 5-year survival rate decreases to 21%. Survival rates correlate with early detection, tumor characteristics, treatment approach, and the patients condition. The 10-year survival rate is 75.7% and the 15-year survival rate is 57.7%. Patients may relapse up to 20 years or more after treatment. 7 5-year survival rate for patients with lesions less than .5cm is 99%, and .5cm larger is 82%. With regional lymph node metastasis, 4.5cm tumors have a 70% incidence rate of nodal involvement, whereas 1.5cm tumors have a 38% incidence rate.7 Location of primary tumor does not directly affect prognosis.⁷
Treatments:
  • Treatment should be based on clinical extent and pathologic characteristics of the tumor, biologic prognostic factors, patient age, and the preference and psychological profile of the patient.
  • Breast conservation therapy is preferred by many patients for T1 and T2 disease.
  • A modified radical mastectomy is recommended, even for small tumors, in any of the following situations:
    • patient preference
    • larger tumors in small breasts in which a lumpectomy would remove so much tissue that the cosmetic outcome would be compromised
    • tumors with high risk for local recurrence
    • diffuse microcalcifications or gross multicentric disease
    • presence of skin or connective tissue diseases that could be complicated by irradiation
    • patient is unreliable for follow-up
  • After radical or modified radical mastectomy, postoperative irradiation of the chest wall and peripheral lymphatics occasionally is indicated in patients with high-risk characterisitcs, regardless of the initial clinical stage or use of adjuvant chemotherapy.
  • Hormonal therapy is used in many patients, particularly those with positive estrogen or progesterone receptors.
  • Node negative patients with tumors less than 2 cm in diameter require adjuvant systemic therapy when high-risk factors are present.
  • Premenopausal patients with positive nodes are treatedw with adjuvant chemotherapy, whereas postmenopausal patients are treated with tamoxifen; some older patients may receive either adjuvant therapy.

Radiation Therapy Techniques
  • The entire breast and chest wall should be included in teh irradiated volume, along with a small portion of underlying lung.
  • Radiopaque surgical clips placed at the margin of the tumor bed may assist in defining the target volume.
  • When combined with a supraclavicular portal, the upper margin of the field is placed at the second intercostal space.
  • If the regional lymph nodes are not irradiated, the upper margin should be placed at the head of the clavivle to include the entire breast.
  • If no internal mammary nodes are treated, the medial margin should be 1 cm over the midline. If an internal mammary field is used, the medial tangential portal is located at th elateral margin of the internal mammary field.
  • The lateral/posterior margin should be placed 2 cm beyond all palpable breast tissue.
  • The inferior margin is 2 to 3 cm below the inframammary fold.
  • In some patients the breast falls superiorly toward the supraclavicular area in the supine position. A thermoplastic mold or an inclinded board placed ont eh treatment table can correct this problem.
  • When treatment is delivered with 6 MV or lower-energy photons in patients with wide, tangential fields, there is significant dose inhomogeneity in the breast, which is correlated with less satisfactory cosmetic results. This problem can be minimized by using higher energy photons to deliver a portion of the breast irradiation to maintain the inhomogeneity throughout the entire breast to 5% or less.
  • Irradiation in the prone position may be used for patients with large, pendulous breasts.
  • Minimal tumor doses of approximately 50 Gy are delivered to the entire breast in 5 to 6 weeks.
  • Minimum doses of 46.8 Gy are preferred for patients with large, pendulous breasts or when irradiation is combined with chemotherapy.
  • It is not necessary to apply bolus to the breast because the skin is usually not at risk for recurrence after complete excision of a T1 or T2 lesion. Use of bolus results in impaired cosmetic results.
  • 65% to 80% of bresat recurrences after conserbation surgery and irradiation occur around the primary tumor site.
  • Boost doses range from 10 to 20 Gy, depending on the size of the tumor and status of excision margins.
  • In the future, some patients may be defined who do not require a boost -- women over 50 with tumors smaller than 1 cm, absence of intraductal carcinoma, negative surgical margins, no necrosis, and low-grade tumors.
  • Brachytherapy boost may be given.¹
TD5/5:
The doses to the following organs should be limited:
Lung -- 1/3 of the volume is 45 Gy; 2/3 is 30 Gy; total is 17.5 Gy
Heart (if left sided breast cancer) -- 1/3 is 60 Gy; 2/3 is 45 Gy; total is 40 Gy¹

Planning Photos:
​Digitally reconstructed radiographs (DRR) demonstrating isodose distribution in a left breast treated with field in field tangents and respiratory gating.⁸
LBrstCoronalISDLRG.jpg
L Breast RG Transverse view isodose lines

LBrstFrontalISDLRG.jpg
L Breast RG Frontal view isodose lines

LBrstSagISDLRG.jpg
L Breast RG Sagittal view isodose lines
References
1. Chao KS, Perez CA, Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002: 345-366.
2. Lenards, N. Clinical Oncology for Medical Dosimetrists: Breast: Stage Tis, T1, and T2 Tumors. Course content - Slides 4, 5, 7. December 2009.
3. Google Images. http://imaging.cmpmedica.com/cancernetwork/cmhb11/11_8_Table7.gif. Accessed January 18, 2010.

4. American Cancer Society. How is Breast Cancer Diagnosed? http://www.cancer.org/docroot/CRI/content/CRI_2_4_3X_How_is_breast_cancer_diagnosed_5.asp . Accessed January 18, 2010.
5. Chen A, Park C, Bevan A, et al. Breast Cancer. In: Hansen EK, Roach M. Handbook of Evidence-based Radiation Oncology, 1st ed: 182-207. New York, NY: Springer, 2007.
6. eMedicineHealth. Breast Cancer. http://www.emedicinehealth.com/breast_cancer/article_em.htm. Accessed January 19, 2010.
7. Washington CM, Leaver D, eds. Principles and Practice of Radiation Therapy, 2nd ed: 844-847. Philadelphia, PA: Mosby Inc, 2004.
8. Digitally Reconstructed Radiographs courtesy of Ginnie Dea, RT(T), Alta Bates Summit Comprehensive Cancer Center.

Ginnie is bright blue.
Bridget is green.
Sheri is brown.
Zack is purple.