Three pieces of good news about advances in breast cancer treatment

Breast cancer is the leading cause of death among women in Brazil and around the world. According to the World Health Organization (WHO), around 2.3 million new cases are diagnosed every year. Here, the National Cancer Institute (INCA) estimates more than 73 thousand new diagnoses in 2025. Even with advances in treatment, more than 15 thousand Brazilian women still die each year due to the disease.

When it comes to breast cancer treatment, there are three main approaches: surgery, which is still essential for curing most patients; radiotherapy, which is used in around 60% of cases as a complement; and systemic therapy, which consists of medications that increase the chances of a cure.

“What has happened in recent decades is that, as we have been subdividing breast cancer into certain characteristics, we have been developing drugs for each of these subtypes. By treating them with the most appropriate drug, we have significantly increased the cure rate for patients,” explains oncologist Rafael Kaliks, a breast cancer specialist at Hospital Israelita Albert Einstein.

Breast cancer is categorized into three major subgroups that guide the initial choice of therapy: tumors with positive hormone receptors (ER+), tumors with positive HER2 (a protein that plays a crucial role in cell growth and development) and the so-called triple negatives, in which the cancer cells do not have estrogen, progesterone or HER2 receptors.

In advanced stages, when the tumor spreads to other organs, the chances of a cure decrease. It is precisely in this scenario that some of the most promising innovations in oncology are concentrated, presented at the latest edition of the American Society of Clinical Oncology (ASCO) congress, the largest global event in the field, which brought together 45,000 doctors and researchers in Chicago, United States, between May 30 and June 3.

Highlights include more individualized strategies based on blood tests and new molecules that extend the time of disease control, reduce side effects and anticipate therapeutic decisions. Below, learn about three results that deserve attention:

1. Early treatment guided by liquid biopsy

One of ASCO’s most talked-about studies tested a simple idea: whether changing treatment before the cancer shows signs of progression can make a difference. In the SERENA-6 clinical trial , women with ER+, HER2-negative metastatic breast cancer were monitored with a periodic blood test, called a liquid biopsy, which can identify a mutation in the ESR1 gene in the circulating tumor genetic material (DNA). This mutation can indicate resistance to hormonal treatment.

“The interesting thing about this work is that, instead of waiting for the clinical progression of the disease (which would manifest itself through symptoms or altered radiological exams), they monitored patients following traditional treatment and measured the presence of the ESR1 gene mutation in their blood every two to three months,” explains Kaliks, who attended the event in Chicago.

When the mutation appeared, even without symptoms or changes in imaging tests, half of the patients changed their medication: they stopped the standard treatment (which consisted of hormone therapy and a cyclin inhibitor) and started taking camisestrant, an oral drug still in the testing phase, in combination with the maintenance of the cyclin inhibitor. The remaining participants continued with the original therapy.

The study showed that bringing forward the switch had an effect: among women who changed therapy, the disease remained under control for 16 months, on average, compared to 9.2 months in the group that followed the traditional approach.

2. New oral drug against hormone resistance

Still keeping an eye on mutations in the ESR1 gene, another clinical study tested a new oral drug that acts differently from current medications: instead of just blocking the estrogen receptor, it destroys it inside the cell.

Called vepdegestrant, the drug was compared to fulvestrant, the standard treatment in these cases. In the results of the investigation, patients who used the new drug were able to control the disease for five months, on average, compared to 2.1 months with the traditional treatment.

3. “Smart drugs” in the first line of treatment

One of the most effective treatments for metastatic HER2-positive breast cancer — one of the most aggressive types of the disease — comes from a strategy that combines precision and potency. Instead of spreading chemotherapy throughout the body, the idea is to target the diseased cells directly, sparing the surrounding cells.

This is the proposal of the so-called antibody-drug conjugates (ADCs), also nicknamed “smart drugs”. A new study presented at Asco evaluated the use of this technology early in the treatment of metastatic disease, instead of leaving it as an option for later stages.

Led by the Dana-Farber Cancer Institute in the US, the clinical trial tested the combination of trastuzumab deruxtecan, which carries the chemotherapy drug to the tumor, with pertuzumab, another anti-Her2 antibody. The result was significant: the risk of disease progression or death fell by 44% compared to standard treatment. In all groups monitored, the disease was controlled for more than three years (median of 40 months).

“Trastuzumab deruxtecan was compared with what had been considered the standard for over 10 years, and it is significantly better. So, this advance should be incorporated in the next one or two years, and we will start to change the sequence of drugs used in HER2-positive metastatic breast cancer,” Kaliks points out. “The concern we still have is about the tolerance of patients to such a prolonged period of use of this medication, which is not without significant toxicities.”

Access is still the main challenge

Despite the enthusiasm, the gap between innovation and clinical reality is still large. The path to a new therapy being available in practice involves regulatory stages, cost-effectiveness analyses, negotiations with the public and private systems, and structural barriers that affect early diagnosis and adherence to treatment. “We leave the conference super excited, but there are still months, sometimes years, before we can put into practice what is presented,” ponders the oncologist.

In Brazil, even drugs already approved by the National Health Surveillance Agency (Anvisa) do not always reach the population quickly enough. This is the case of trastuzumab deruxtecan, approved in 2024 but not yet incorporated into the Unified Health System (SUS).

According to the Brazilian Society of Clinical Oncology (SBOC), approximately 70% of cancer patients in the country depend exclusively on the public system. Even among those who have health insurance, there is not always a guarantee of coverage for high-cost therapies — in the United States, treatment with trastuzumab deruxtecan can cost up to US$166,000 per year.

“Today, in Brazil, between 50% and 60% of breast cancer cases will be cured. But if we have a reality in which there is adherence to screening, rapid access to diagnosis and complete access to treatment, this figure will exceed 80%,” says Kaliks.

Despite the challenges in accessing and incorporating new therapies, the oncology scenario is experiencing an optimistic moment. Recent discoveries are extending the period of disease control while opening up prospects for cure in cases for which this was not previously considered.

In the early stages, treatments are becoming less invasive and more effective, with smaller surgeries, less need for radiotherapy and lighter pre-operative protocols. In advanced cases, new drugs are prolonging survival and offering patients a better quality of life — a paradigm shift that is likely to become more consolidated in the coming years.

“Breast cancer, which is already a highly curable disease, will become even more curable,” says the Einstein doctor. “We are beginning to believe that, for some patients with metastatic disease, which until now was considered incurable, a cure may become a real possibility in the not-so-distant future.”

Source: Einstein Agency

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