What’s New in Oncology

Improvements in breast cancer screening and treatments are decreasing breast cancer mortality. In a study using four simulation models of breast cancer mortality rates in the United States (US), breast cancer screening and treatment in 2019 were associated with a 58 percent reduction in US breast cancer mortality compared with 1975 [1]. Approximately half of this reduction was due to treatment of early breast cancer, while the rest was divided roughly equally between treatment of metastatic breast cancer and breast cancer screening. We support breast cancer screening for appropriate candidates and incorporate novel, data-driven strategies into our treatment recommendations for breast cancer.

Trials are examining omission of radiation in early, favourable-risk breast cancer

➢ In a single-arm trial including 500 females ≥55 years with T1N0, grade 1 or 2, luminal A-breast cancer, breast-conserving surgery and endocrine therapy without radiation were associated with a low incidence of local recurrence at five years (2.3%).

➢ A prospective study found that patients ≥50 years with nontriple negative cT1N0 breast cancer that was unifocal on preoperative MRI and pT1N0 or N1mi at the time of surgery could omit adjuvant radiation and experience a low ipsilateral invasive recurrence rate (1 percent at five years).

We consider omission of adjuvant radiation to be an option in women ≥65 years with clinically node-negative, small (tumor size <3 cm), hormone receptor-positive, HER2-negative breast cancer who are willing to take adjuvant endocrine therapy, but we await further data before omitting radiation in other patients. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Possible omission of RT for select ER-positive, HER2-negative cancers'.)

Regional Nodal Radiation in early Breast Cancer (November-2023)

Studies are evaluating the impact of adjuvant regional nodal radiotherapy (RT) in patients with early breast cancer. In a meta-analysis including over 12,000 patients, absolute improvements in breast cancer recurrence and mortality from regional nodal RT in trials from the 1990s through 2000s were greatest for patients at highest risk for recurrence; absolute reductions in 15-year breast cancer mortality were 1 to 2 percent among those with no positive axillary lymph nodes, 2 to 3 percent among those with one to three positive nodes, and 4 to 5 percent for those with four or more positive nodes. However, no benefits were observed in earlier trials of nodal RT. The discrepancy is likely due to refinements in radiation techniques. For patients with node-positive or high-risk node-negative breast cancer, we offer adjuvant regional nodal RT.

Peritumoral lidocaine injection before incision for breast cancer surgery (September 2023)

In a multicenter, randomized trial of over 1000 patients with early breast cancer undergoing mastectomy or breast-conserving surgery, peritumoral injection of 0.5% lidocaine prior to incision improved five-year disease-free survival (87 versus 83 percent) and five-year overall survival (90 versus 86 percent). The mechanism is unknown but thought to involve blocking voltage-gated sodium channels and thereby preventing activation of prometastatic pathways. The trial protocol for surgical management of breast cancer deviated from what may be considered standard treatment in many clinical practices, so further validation is necessary; however, peritumoral injection of lidocaine may be a reasonable intervention given its simplicity and minimal cost. (See "Breast-conserving therapy", section on 'Incision'.).

Sacituzumab govitecan in hormone receptor-positive, HER2-negative metastatic breast cancer (August 2023)

Sacituzumab Govitecan (SG) is an antibody-drug conjugate that previously showed progression-free survival benefits over clinician's choice of therapy in patients with metastatic, heavily pretreated, hormone receptor (HR)-positive, HER2-negative breast cancer; overall survival results from that randomized trial are now available. Among 543 patients, the overall survival with SG was 14.4 versus 11.2 months with clinician's choice of therapy. SG has regulatory approval in the United States for patients with unresectable locally advanced or metastatic HR-positive, HER2-negative breast cancer who have received endocrine-based therapy and at least two additional systemic therapies in the metastatic setting. (See "Endocrine therapy resistant, hormone receptor positive, HER2-negative advanced breast cancer", section on 'Sacituzumab govitecan'.) 

Pretreatment staging of locally advanced breast cancer (August 2023)

For patients with locally advanced breast cancer, pretreatment imaging is typically obtained to rule out metastatic disease, but the optimal modality is under investigation. In a randomized trial in 369 patients with stage III or IIb (T3N0, but not T2N1) breast cancer, 23 percent of patients assigned to staging with positron emission tomography-computed tomography (PET-CT) were upstaged to stage IV compared with 11 percent assigned to CT of the chest, abdomen, and pelvis (CT C/A/P) and bone scan [9]. This resulted in changes in treatment strategy, such that fewer patients in the PET-CT group received combined modality therapy (81 versus 89 percent). For patients with stage IIIA or higher disease, regardless of whether symptoms are present, we obtain a whole body PET-CT for staging, but we consider a bone scan plus CT C/A/P to be a reasonable alternative. (See "Clinical features, diagnosis, and staging of newly diagnosed breast cancer", section on 'Role of imaging'.)

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