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FACT SHEET: Breast Cancer1 (includes a variety of carcinomas, such as “infiltrating ductal”, “infiltrating lobular”, “medullary”, “mucinous”, and “tubular”)

Date of Publication: January 23, 2019

Note: The therapeutic modalities of chemotherapy and radiation therapy are addressed in detail in separate fact sheets.

Is the initiation of non-invasive dental hygiene procedures* contra-indicated?

Is medical consult advised?  

  • Yes, if the patient/client is about to undergo, or is undergoing, radiation therapy.
  • Yes, if the patient/client is undergoing chemotherapy and has, or is suspected to have, certain oral conditions or systemic manifestations.
  • Yes, if the patient/client is taking a bone antiresorptive agent, such as a bisphosphonate (either orally or by injection) or denosumab.  
  • Yes, if the patient/client appears debilitated.
  • Yes, prior to dental hygiene procedures, if permanent seed interstitial brachytherapy2 has taken place within the past two months in a patient/client and you, the dental hygienist, are, or may be, pregnant. In such a circumstance, input should be sought from a radiation oncologist regarding radiation safety precautions.

Is the initiation of invasive dental hygiene procedures contra-indicated?**

  • Yes, if the patient/client is undergoing radiation therapy and/or chemotherapy.
  • Yes, if the patient/client has MRONJ (as can be the case in advanced breast cancer, depending on treatment).

Is medical consult advised? 

  • See above. Additionally, pre- and post-radiotherapy/chemotherapy medical and/or dental consultation is often warranted.

Is medical clearance required? 

  • Yes, if the patient/client is undergoing radiotherapy and/or chemotherapy.
  • Yes, if MRONJ exists or is suspected.
  • Yes, if patient/client is being treated with medications associated with immunosuppression +/- increased risk of infection and/or adrenal suppression (e.g., corticosteroids are used as part of some regimens in the treatment of breast cancer).

Is antibiotic prophylaxis required?  

  • Possibly, for some patients/clients undergoing radiotherapy and/or chemotherapy according to blood indices and/or delivery mechanism (e.g., in-dwelling central venous catheter or port). Also, persons who have had radiotherapy to the left breast and chest are at increased risk of valvular heart disease, and they may be candidates for prophylaxis against infective endocarditis (e.g., if they have prosthetic cardiac valve or material).

Is postponing treatment advised?

  • Possibly, depending on blood indices (which indicate degree of immunosuppression and/or thrombocytopenia3) in patients/clients undergoing radiotherapy or chemotherapy. Elective invasive procedures should be deferred until after radiation- or chemo-induced immunosuppression ceases.
  • Potentially, if MRONJ exists, informed by medical/dental consultation. Ideally, all necessary invasive dental and dental hygiene treatments should be performed before administration of injectable bisphosphonate drugs.
  • Potentially, if permanent seed interstitial brachytherapy has taken place within the past two months in a patient/client and you, the dental hygienist, are, or may be, pregnant.

Oral management implications

  • Refer also to Radiation Therapy, Chemotherapy, Xerostomia, and/or MRONJ Fact Sheets, as applicable.
  • Metastatic disease to the mandible or maxilla may uncommonly be the first sign of malignancy, including breast cancer. If undiagnosed metastatic cancer of the jaw (or elsewhere in the oral cavity) is suspected, prompt medical referral is indicated for work-up to identify the primary site and to stage the degree of metastatic involvement (i.e., solitary jaw lesion or, more commonly, a clinical sign of disseminated skeletal disease).
  • Oral assessment before, during, and after active chemotherapy and radiotherapy is important. Coordination of care between the oncology and oral health teams is essential for patient/client safety.
  • Post-operatively, dental hygiene appointments should be kept short as the patient/client deals with fatigue. Furthermore, dyspnea (shortness of breath) may occur after radiotherapy for breast cancer due to acute radiation pneumonitis4.
  • Because patients/clients who receive axillary surgery and/or radiation are at risk of lymphedema5, blood pressure (BP) measurements should ideally be avoided on the affected arm(s). Patients/clients who have undergone bilateral axillary lymph node dissection may require BP readings on their leg.
  • Patients/clients taking aromatase inhibitors may experience wrist/hand/finger dysfunction that compromises ability to brush and floss teeth. Appropriate educational and treatment interventions should be undertaken to support such persons.

Oral manifestations

  • Refer also to Radiation Therapy, Chemotherapy, Xerostomia, and MRONJ Fact Sheets for details regarding cancer treatment-related dry mouth, caries, mouth sores, gingival bleeding, dysgeusia (unpleasant taste), infections, periodontitis, tooth decay, and osteonecrosis. 
  • While cancer metastases to the mandible and maxilla are unusual, about 1% of all malignant neoplasms do metastasize to the jaws6. About 80% of these metastases affect the mandible7, 14% affect the maxilla, and 5% affect both jaws. In women, primary breast cancer accounts for about 42% of jaw metastases.
  • Persons more likely to be affected by metastatic breast cancer to the jaws are in the older age brackets, which reflects the higher prevalence of malignancy in this population. The prognosis for patients/clients with metastatic carcinoma of the jaws is poor, with 5-year survival rates in the 10% range.
  • Most metastatic jaw lesions involve one oral site, with only a few occurring in 2 or 3 sites.
  • Bone pain, tooth ache, loosening of teeth, bone (and hence jaw) swelling, lip or chin paresthesia, gingival mass, trismus, and pathologic fracture may result from metastatic jaw lesions. Radiographically, most metastases appear as poorly marginated, radiolucent, osteolytic defects. However, bone metastases of breast cancer, depending on type, may also be osteoblastic, in which case fairly well circumscribed radiodense (i.e., radiopaque) lesions may be seen.
  • More rarely, metastatic deposits occur in the gingiva (especially the attached gingiva, with hyperplastic or reactive lesions initially resembling the clinical appearance of pyogenic granuloma8 and periodontal abscess). Metastatic lesions in other areas of the oral soft tissues tend to manifest as submucosal masses, particularly in the tongue, with very occasional presentation as ulcers.
  • Oral metastases can grow rapidly, causing pain, difficulty in chewing, dysphagia, disfigurement, and intermittent bleeding.
  • Medication-related osteonecrosis of the jaw may occur secondary to medications used to manage metastatic cancer affecting the bones. Osteonecrosis may also be caused by metastatic disease itself.
  • Estrogen deficiency (which is induced by certain treatments — such as selective estrogen receptor modulators [SERMs], aromatase inhibitors [AIs], and selective estrogen degraders (SERDs) — may increase risk of periodontal disease (including periodontal pocketing), as well as promote gingival bleeding, tooth loss, alveolar bone loss, xerostomia, oral dysesthia (abnormal sensation), taste alteration, and burning mouth syndrome. 
  • Breast cancer treatments that decrease estrogen levels may increase the risk of soft tissue complications.
  • White spots in the mouth or on the lips are a side effect of treatment with tamoxifen (a SERM), letrozole (an AI), trastuzumab (a monoclonal antibody), fulvestrant (a SERD), and lapatinib (a signal transduction inhibitor).
  • Sore throat is a side effect of various SERMs, AIs, SERDs, trastuzumab, and leuprolide (a luteinizing hormone-releasing hormone agonist [LHRH agonist]).
  • Cracked lips are a side effect of treatment with trastuzumab. 

Related signs and symptoms

  • Refer also to Radiation Therapy and Chemotherapy Fact Sheets.
  • Excluding non-melanoma skin cancer, breast cancer (BC) is the most commonly diagnosed cancer among Canadian women, accounting for 25% of all new cancer cases in females. 1 in 8 Canadian women will develop breast cancer in her lifetime. Annually, about 11,000 women are diagnosed in Ontario (27,700 in Canada), and 2,100 (5,400) die from the disease. The 5-year net survival rate is 89%.
  • Incidence increases with age, with most cases occurring in post-menopausal women. Family history of the disease is an important risk factor, with 5% to 10% of cases arising in high-risk families. Other risk factors include early menarche, late menopause, nulliparity (not bearing children), smoking, past history of radiation exposure, sedentary lifestyle, exposure to hormones, and alcohol consumption. 
  • While the vast majority of breast cancer occurs in women, it can also uncommonly occur in men (1% of diagnoses, representing about 100 cases annually in Ontario [260 in Canada]). Male breast cancer tends to be aggressive in nature.
  • Signs/symptoms of BC include lump in the breast with or without discharge, breast skin or nipple changes, and breast pain.
  • Asymptomatic breast cancer may be discovered with mammography, which can detect radiographic changes suggestive of cancer. Cancer Care Ontario (Ontario Health) recommends population-based mammographic screening every two years for women aged 50 to 74 years who are at average risk for breast cancer.
  • Breast cancer is particularly likely to give rise to skeletal metastases, and bone pain in a common result. Metastasis usually occurs after BC becomes clinically detectable and is primarily to regional lymph nodes and within the chest wall, bone9, liver, and lung. At present, metastatic breast cancer is not curable, but it is treatable.
  • For patients/clients with BC, depending on individual circumstances, treatment options might include one or more of: lumpectomy (surgical removal of a breast lump); radiation therapy (external beam to breast, chest wall, and/or local lymph nodes and/or brachytherapy); mastectomy (surgical removal of the breast); axillary node dissection; hormone therapy (i.e., anti-estrogen10 therapy, including 1/ selective estrogen receptor modulators such as tamoxifen, raloxifene, and toremifene, 2/ aromatase inhibitors such as anastrozole, exemestane, or letrozole, and 3/ selective estrogen degraders such as fulvestrant); chemotherapy; immunotherapy; targeted therapy; bone-directed treatment (e.g., bisphosphonates or denosumab); and pain management and other palliative care. In premenopausal women, ablation of ovarian estrogen production may be accomplished by bilateral oophorectomy (surgical removal of the ovaries), radiation, or chemical means (e.g., with luteinizing hormone-releasing hormone agonists such as goserlin or leuprolide). 
  • Arm swelling due to lymphedema often occurs after breast cancer surgery and/or radiotherapy.
  • In pre-menopausal women, anti-estrogen therapies are associated with bone loss leading to osteoporosis and reduction in bone mineral density (BMD). They may also contribute to fatigue and depression.
  • Aromatase inhibitor use leads to musculoskeletal toxicity in up to 50% of patients/clients. This includes joint stiffness, arthralgias, and myalgias, particularly of the wrists, hands, and fingers.

References and sources of more detailed information

Date: December 4, 2017
Revised: February 26, 2022


1 Cancerous cells are characterized by uncontrolled growth, abnormal structure, and the ability to move into other parts of the body (invasiveness and metastasis).
2 Brachytherapy can involve either temporary or permanent radioactive seed implantation near or within cancerous tissue (interstitial brachytherapy) or radioactive seed placement within a body cavity (intracavitary brachytherapy). Permanent breast seed implant (PBSI) entails the permanent placement of low-dose radioactive seeds to prevent cancer recurrence in a person with early-stage breast cancer.
3 thrombocytopenia = low blood platelet count
4 Pneumonitis is inflammation of lung tissue. Irradiation of breast tissue is often associated with radiation exposure to lung tissue.
5 Lymphedema is the accumulation of lymph fluid in interstitial tissue. It can be exacerbated by squeezing lymph channels with a blood pressure cuff.
6 The mechanism of spread to the jaws is usually hematogenous (i.e., via the blood stream) from the primary neoplasm or from lung metastases.
7 The premolar region, the angle, and the body of the mandible are most commonly affected by metastatic disease.
8 Pyogenic granuloma is a benign, vascular “overgrowth” lesion that occurs on the mucosa or skin due to irritation, physical trauma, or hormonal factors.
9 Bone metastases from BC are particularly common in the ribs, spine, pelvis, and long bones of the upper and lower extremities.
10 Many breast cancers are exacerbated by estrogen.

* Includes oral hygiene instruction, fitting a mouth guard, taking an impression, etc.
** Ontario Regulation 501/07 made under the Dental Hygiene Act, 1991. Invasive dental hygiene procedures are scaling teeth and root planing, including curetting surrounding tissue.