Mortality of COVID-19 is increased when certain co-morbidities, among others advanced malignancies are present. Deleterious effect of cytotoxic therapy, related to its immunosuppressive effect, may also be hypothesised. However, postponing or cancelling oncologic treatment, especially in younger patients with advanced and more aggressive tumors may worsen the prognosis. The case of a 39-year-old female patient is presented, who was diagnosed with loco-regionally advanced breast cancer during the pandemic. Primary systemic chemotherapy was started. The patient presented with acute respiratory tract symptoms during the fifth cycle and subsequently SARS-CoV-2 infection was diagnosed. Chemotherapy was cancelled. Symptoms resolved in three days after diagnosis. SARS-CoV-2 PCR remained positive up to day 43. Antihormonal therapy was introduced on day 19 and she underwent mastectomy with axillary lymph node dissection on day 51. Chemotherapy was reset postoperatively on day 82 with prophylactic G-CSF protection. No adverse event was observed throughout the treatment. Cytotoxic chemotherapy and surgery can be successfully delivered in breast cancer patients with prolonged asymptomatic SARS-CoV-2 PCR positivity, even without negative swab result. Individual optimisation of the therapy may require deviations from standard protocols. Closer multidisciplinary cooperation may contribute to the minimisation of both oncologic and infectious risks.