From Breast Cancer Diagnosis to Treatment: How Prosigna® Supports Clinical Decision-Making

Receiving a breast cancer diagnosis often raises many questions, especially regarding the next steps and available treatment options. Although tests such as mammography, ultrasound, and biopsy are essential for identifying and characterizing the tumor, they do not always provide all the information needed to guide the most appropriate therapeutic strategy. This is because tumors with similar clinical characteristics may present distinct biological behaviors and different risks of recurrence.

In this context, genomic tests have gained prominence in personalized medicine by providing complementary information about tumor biology. Among these tools is Prosigna® (PAM50), a test that evaluates the expression of 50 genes associated with breast cancer and may help estimate the risk of recurrence in specific patient populations.

In this article, we explain how breast cancer is diagnosed, which tumor characteristics influence treatment decisions, and how genomic tests, such as Prosigna®, contribute to an increasingly individualized approach.

How is breast cancer diagnosed?

Breast cancer diagnosis occurs through different stages with the goal of identifying suspicious changes, confirming the presence of disease, and characterizing the tumor.

In simplified terms, the process typically involves:

• Clinical evaluation;
• Imaging tests;
• Classification of radiological findings;
• Biopsy;
• Pathology examination;
• Biomarker assessment;
• Molecular or genomic testing, when indicated.

The investigation may begin after the perception of signs or symptoms or during screening examinations performed in individuals without manifestations of the disease.

Among the signs that warrant medical evaluation are:

• Presence of a breast lump;
• Changes in the skin of the breast;
• Nipple retraction;
• Spontaneous nipple discharge;
• Changes in the armpit (axillary region);
• Changes in breast shape or size.

Early diagnosis remains one of the most important strategies for improving treatment outcomes, as identifying the disease at earlier stages is associated with higher survival rates and better therapeutic results (1, 2).

Each of these steps involves specific tests and criteria, ranging from the initial clinical assessment to confirmation through biopsy. To learn more about how this process works in practice, including the signs that warrant medical attention, check out our full article: Breast Cancer Diagnosis: How Is It Made?.

Screening and early diagnosis are not the same thing

Although frequently used as synonyms, screening and early diagnosis represent different approaches. Screening aims to identify suspicious changes in individuals without symptoms, with the goal of detecting findings suggestive of cancer, whereas early diagnosis is related to the prompt investigation of signs and symptoms that are already present (3).

Mammography is the main imaging modality used in population-based breast cancer screening programs and plays a key role in detecting the disease at early stages (4).

What happens after the diagnosis is confirmed?

Once the presence of breast cancer has been confirmed, additional analyses are performed to better understand the characteristics of the tumor.

Key evaluations include:

• Histological type;
• Tumor grade;
• Hormone receptors (estrogen and progesterone);
• HER2 status;
• Lymph node involvement;
• Disease stage.

This information helps estimate prognosis and guides the selection of the most appropriate treatment options (5).

However, even patients whose tumors share similar clinical and pathological characteristics may present different biological behaviors, treatment responses, and clinical outcomes. Recognizing this heterogeneity contributed to the development of tools capable of characterizing deeper aspects of tumor biology, including gene expression profiles and molecular signatures with prognostic and predictive potential (5, 6).

Why can patients with similar tumors receive different treatments?

Breast cancer is not a single disease (6). Two tumors may have a similar size, the same hormone receptor status, and comparable pathological characteristics, yet still exhibit different biological behaviors (6, 7).

These differences help explain why patients with similar clinical characteristics may have different risks of recurrence and responses to available therapies.

Advances in molecular biology have enabled a better characterization of this heterogeneity, leading to the identification of different molecular subtypes and the development of tools capable of providing additional prognostic and predictive information (6). This knowledge has contributed to the advancement of personalized medicine strategies, in which the biological characteristics of the tumor are considered in treatment decision-making.

The role of genomic tests in breast cancer

Genomic tests evaluate the expression of genes present in the tumor itself. Unlike traditional tests, which analyze morphological and immunohistochemical characteristics, these tools provide information about the biological activity of the tumor.

Their objective is not to diagnose cancer, but rather to complement the information already available in order to support prognostic assessment and clinical decision-making (8, 9).

Currently, several international guidelines recognize the utility of genomic tests in specific scenarios of early-stage HR-positive and HER2-negative breast cancer (8).

Are genetic tests and genomic tests the same thing?

No. Genetic tests investigate inherited alterations associated with the risk of developing cancer, such as variants in the BRCA1 and BRCA2 genes. Genomic tests, on the other hand, analyze tumor tissue after diagnosis and provide information about the biological behavior of an already established cancer.

Although both use information related to DNA or genes, they have different clinical objectives and answer different questions.

This distinction is particularly important for patients with a family history of the disease, as genetic testing can help identify an inherited predisposition even before a diagnosis is made. To understand how this process works and who should consider undergoing this evaluation, read our content on: Genetic Testing for Hereditary Breast Cancer: How It Works and Who Should Be Tested.

Molecular subtypes: understanding tumor biology

One of the most important advances in understanding breast cancer biology was the identification of the so-called intrinsic or molecular subtypes.

The intrinsic subtypes most commonly used in current classification systems, which reflect biological differences among tumors, include:

• Luminal A;
• Luminal B;
• HER2-enriched;
• Basal-like.

This classification was initially described by Perou and colleagues through gene expression studies and helped transform the understanding of breast cancer from a relatively homogeneous disease into a group of biologically distinct tumors (10).

The identification of these subtypes revealed biologically relevant differences among tumors and may provide additional prognostic information beyond conventional clinicopathological characteristics, contributing to a more individualized understanding of the disease.

What is Prosigna® (PAM50)?

Prosigna® is a genomic test based on the PAM50 molecular signature. Performed using a sample of already diagnosed tumor tissue, the test evaluates the expression of 50 genes related to the biological behavior of breast cancer. The test was developed to identify the intrinsic subtypes of the tumor and generate a prognostic score called Risk of Recurrence (ROR) (11).

Among the information provided by the test are:

• Identification of the intrinsic subtype;
• Classification as Luminal A, Luminal B, HER2-enriched, or Basal-like;
• Risk of Recurrence (ROR) score;
• Estimation of distant recurrence risk in populations for which the test has been validated (11).

Several studies have demonstrated that the information generated by PAM50 adds prognostic value beyond the clinical factors traditionally used (11, 12).

What is the ROR score?

The ROR (Risk of Recurrence Score) is a prognostic indicator calculated from the gene expression profile evaluated by Prosigna®. Its purpose is to estimate the risk of distant disease recurrence over time, complementing information obtained from characteristics such as tumor size, histological grade, and lymph node status.

It is important to emphasize that the result does not predict with certainty whether the disease will return. Rather, it is a statistical estimate based on large patient populations that have been studied and validated across different clinical cohorts (11, 12).

Who may be eligible for Prosigna®?

Prosigna® was developed for use in specific clinical contexts, mainly in patients with early-stage hormone receptor-positive (HR+) and HER2-negative breast cancer.

The decision to request the test should always take into account the individual clinical context, the tumor’s pathological characteristics, and current guideline recommendations (8, 9).

How can genomic tests help guide treatment decisions?

Historically, decisions regarding adjuvant treatment were based primarily on clinical and pathological factors.

Although these parameters remain essential, they do not capture the full biological complexity of the tumor.

Genomic tests add a complementary layer of information by evaluating gene expression patterns related to tumor biology. As a result, certain tests may contribute to a more individualized estimate of recurrence risk and, in specific clinical scenarios, support discussions regarding the need for particular therapeutic strategies (13).

No decision should be made based exclusively on a molecular test. Results should always be interpreted together with all other available clinical data (8, 14).

What did the OPTIMA study show about the use of Prosigna®?

The OPTIMA (Optimal Personalised Treatment of Early Breast Cancer Using Multi-Parameter Analysis) study is a prospective, randomized trial that evaluated a treatment strategy guided by the Prosigna® Risk of Recurrence (ROR) score in patients with early-stage ER-positive and HER2-negative breast cancer considered clinically at higher risk of recurrence.

Results presented at the ASCO Congress in 2026 included 4,429 patients who were initially considered candidates for chemotherapy based on traditional clinical criteria. In the group whose treatment strategy was guided by Prosigna®, 68% had tumors with an ROR ≤60. Five-year invasive breast cancer-free survival was similar between the test-guided strategy group and the conventional treatment group, meeting the predefined criterion for non-inferiority (15).

These results demonstrate the potential of the ROR score as a complementary tool to clinicopathological assessment, contributing to more individualized risk stratification and to decision-making regarding adjuvant therapy.

The findings also reinforce the role of molecular characterization in the individualized assessment of breast cancer, showing that information obtained from gene expression can complement the clinical and pathological factors traditionally used in decision-making.

These results are consistent with previous evidence demonstrating the prognostic value of PAM50/ROR. In analyses from the ABCSG-8 and ATAC studies, ROR added prognostic information beyond conventional clinical factors and identified patient groups with significant differences in the risk of distant recurrence at 10 years (12).

Prosigna® at SYNLAB

Advances in precision medicine are transforming the way breast cancer is evaluated and treated. In addition to information obtained through clinical, pathological, and immunohistochemical examinations, genomic tests provide a deeper understanding of tumor biology and the risk of disease recurrence.

SYNLAB offers Prosigna® (PAM50), a genomic test developed to support the prognostic assessment of patients with early-stage HR-positive and HER2-negative breast cancer in specific clinical scenarios. Performed using a sample of tumor tissue, the test provides complementary information about the molecular subtype and recurrence risk (ROR), contributing to a more individualized assessment of recurrence risk and supporting clinical decision-making.

Get to Know SYNLAB Group, a Reference in Medical Diagnostic Services!

Performing precise and updated tests is essential for more accurate diagnoses and better treatment guidance. SYNLAB is here to help you.

We provide diagnostic solutions with strict quality control to the companies, patients, and physicians we serve. We have been in Brazil for over 10 years, operate in 36 countries across three continents, and are leaders in service provision in Europe.

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Frequently Asked Questions (FAQ)

How is breast cancer diagnosed?

Diagnosis involves clinical evaluation, imaging tests, biopsy, and analysis of tumor tissue to confirm the presence of the disease and characterize the tumor.

Which test confirms a breast cancer diagnosis?

Confirmation is obtained through a biopsy, followed by pathological examination of the collected tissue sample.

What is the difference between screening, early diagnosis, and diagnostic confirmation?

Screening aims to identify abnormalities in people without symptoms. Early diagnosis occurs when signs or symptoms are promptly investigated. Diagnostic confirmation is achieved through biopsy and tumor tissue analysis.

What are molecular or genomic tests in breast cancer?

These are tests that analyze the expression of genes within the tumor itself to provide additional information about its biological behavior and risk of recurrence.

Is a genomic test the same as a BRCA genetic test?

No. Genetic tests evaluate inherited alterations, such as variants in the BRCA1 and BRCA2 genes. Genomic tests analyze an already diagnosed tumor.

What is Prosigna® (PAM50) and what is it used for?

Prosigna® is a genomic test that evaluates the expression of 50 genes associated with breast cancer. It helps identify the tumor’s molecular subtype and estimate the risk of recurrence.

What does the Risk of Recurrence (ROR) score mean?

The ROR (Risk of Recurrence Score) is a prognostic score that estimates the risk of distant disease recurrence based on the biology of the tumor.

What are the molecular subtypes of breast cancer?

The current main molecular subtypes are Luminal A, Luminal B, HER2-enriched, and Basal-like.

For which patients may Prosigna® be considered?

The test may be considered for patients with early-stage hormone receptor-positive (HR+) and HER2-negative breast cancer, according to medical evaluation and current recommendations.

Does Prosigna® detect breast cancer or evaluate the tumor after diagnosis?

Prosigna® is not a diagnostic test. It is performed after breast cancer has been confirmed to evaluate biological characteristics of the tumor.

Does the test use blood or tumor tissue?

The test is performed using a sample of tumor tissue obtained during a biopsy or surgery.

Can a genomic test help inform chemotherapy decisions?

In specific situations, test results can provide complementary information about recurrence risk and support discussions regarding therapeutic strategies, always in conjunction with other clinical and pathological data.

References

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