Even Small Breast Cancer Tumors Can Be Aggressive

Tumor biology and size should guide breast cancer treatment.

Despite their small size, early-stage breast cancer tumors may still be aggressive and threaten patient outcomes. A new study presented at the European Society for Medical Oncology (ESMO) found that 1 in 4 small-sized tumors were aggressive and benefited from receiving chemotherapy.

Importantly, identifying potentially aggressive small tumors can be accomplished through a 70-gene signature, according to the study authors.

“Our results challenge the assumption that all small tumours [sic]are less serious and do not need adjuvant chemotherapy,” said lead study author Dr Konstantinos Tryfonidis.

Included in the MINDACT study were 6693 women with early-stage breast cancer, defined as lymph node negative or 1 to 3 lymph node positive, according to the study.

The findings of MINDACT indicated that 46% of patients at high risk of recurrence (defined through Adjuvnt! Online technology) may not require chemotherapy. Additionally, MammaPrint indicated that the women had a low genetic risk of recurrence.

The new sub analysis included only 826 patients with primary tumors less than 1 cm in size. The authors examined clinical and genomic risks, which showed that 24% of patients had a low clinical and high genomic risk of cancer recurrence. The patients were then randomized to receive chemotherapy or to not receive the treatment.

The authors discovered that at 5 years, few patients who received chemotherapy experienced a relapse.

“We found that nearly 1 in 4 patients with small tumours [sic] are at risk of distant metastases and do benefit from chemotherapy,” said senior study author Dr Fatima Cardoso, MD.

These patients were also found to have high rates of distant metastases-free survival, disease-free survival, and overall survival, confirming the benefit of chemotherapy, according to the study.

“This was striking because based on clinical criteria alone you would say that these tumours [sic] are not aggressive and therefore patients do not need chemotherapy,” Dr Cardoso said. “But 24% of small tumours [sic] had an aggressive biology, which shows that not all small tumours [sic] are the same.”

These findings highlight that tumor size and biology is important for treating patients with breast cancer.

“Small node negative tumours [sic] can be very aggressive, even if they are classified as clinical low risk,” said Evandro de Azambuja, MD, PhD, commenting on behalf of ESMO. “Tumour [sic] biology needs to be taken into account when deciding adjuvant treatments in this patient population. One cannot forget the patient’s age, performance status, comorbidities and preferences during the discussion.”