Can AI Help Some Women Avoid Chemotherapy? Here's How Recurrence-Risk Tests Are Changing Breast Cancer Treatment

For decades, doctors have relied on clinical factors such as a patient's age, tumour size, tumour grade, lymph node involvement and immunohistochemistry (IHC): a laboratory technique that detects specific proteins in tumour tissue, including Ki-67, a marker of how quickly cancer cells are growing. These factors have long guided breast cancer treatment. However, they do not always reveal how aggressive a tumour truly is. As a result, two women with seemingly similar clinical profiles can have very different risks of recurrence.

“In India, about 90-95% of women with early-stage hormone receptor-positive, HER2-negative breast cancer have traditionally received chemotherapy because there was no practical and affordable way to identify those who could safely avoid it,” says Dr Manjiri Bakre, Indian Institute of Science (IISc) scientist, Founder and CEO of OncoStem Diagnostics, and developer of the CanAssist Breast (CAB) test.

Developed by Bengaluru-based OncoStem Diagnostics, CanAssist Breast is an artificial intelligence-powered test that analyses tumour biology using IHC. It estimates the likelihood of cancer recurrence and helps doctors identify which women with early-stage breast cancer are likely to benefit from chemotherapy... and who may safely avoid it and receive hormone therapy alone.

Identifying Patients Who May Not Need Chemotherapy

Traditionally, women with breast tumours larger than 0.5 cm have often been advised to undergo chemotherapy, notes Dr Jayanti Thumsi, Group Lead – Robotic Breast Surgery, HCG Hospital, Bengaluru. However, she says that treatment decisions should be based not only on tumour size but also on its biological behaviour, alongside other clinical factors.

Recurrence-risk testing is particularly useful for women with early-stage hormone receptor-positive, HER2-negative breast cancer, including those with tumours up to 5 cm and limited lymph node involvement. By assessing tumour biology rather than relying solely on conventional clinical features, the test helps doctors determine whether chemotherapy offers any meaningful benefit beyond hormone therapy.

How CanAssist Breast Works

According to Dr Bakre, CanAssist Breast analyses five protein biomarkers alongside standard clinical information using a validated AI algorithm to predict the risk of recurrence. Unlike AI systems that continue to learn and evolve, the CAB algorithm is a fixed (locked) model, ensuring consistent and reproducible results. She stressed that the test is designed to support—not replace—clinical judgement. Doctors still consider factors such as the patient's age, overall health, medical history and other clinical findings before recommending treatment.

Dr Tanay Shah, Consultant Surgical Oncologist, HCG Aastha Cancer Centre, Ahmedabad, explains that hormone therapy refers to anti-estrogen treatment. Based on the CanAssist Breast score, clinicians estimate a patient's risk of recurrence over five years. If chemotherapy is expected to significantly reduce that risk, it is recommended. Otherwise, hormone therapy alone may be sufficient. Recurrence-risk tests were initially used mainly for postmenopausal women or those with significant medical conditions who were less suitable for full-dose chemotherapy.

Validated for Indian Patients

While international studies such as TAILORx have shown that many women with early-stage breast cancer may not benefit from chemotherapy, applying these findings in India has not always been straightforward. Dr Bakre explains that many internationally available recurrence-risk tests were developed using data from Western populations, are expensive and often require tumour samples to be shipped overseas, increasing both costs and turnaround time.

Dr Thumsi points out that CanAssist Breast has been validated in Indian patients, making it particularly relevant for Indian clinical practice. Differences in genetics, lifestyle and environmental factors may influence tumour biology, making population-specific validation valuable for treatment decisions.

Clinical Evidence Behind Recurrence-Risk Testing

Recurrence-risk tests including CanAssist Breast and international tests such as Oncotype DX, Prosigna and MammaPrint are helping personalise breast cancer treatment. While most international tests analyse gene activity, CanAssist Breast uses IHC to study proteins expressed within the tumour. The test is performed on tumour tissue removed during surgery and combines laboratory findings with AI-based analysis to estimate recurrence risk.

Supported by extensive clinical research and incorporated into treatment guidelines in India and internationally, these tests allow doctors to personalise treatment instead of relying solely on traditional clinical features. Dr Shah said his team has performed around 160 CanAssist Breast tests, with patients followed for up to six years. The outcomes have been reassuring, with no significant increase in cancer recurrence. The test gives both, doctors and patients, greater confidence when chemotherapy is unlikely to provide additional benefit.

Dr Bakre recalled the case of a young woman with Stage II breast cancer who wished to have children. Under conventional treatment protocols, chemotherapy would typically have been recommended. However, her CanAssist Breast results showed a low risk of recurrence, allowing her to safely avoid chemotherapy. She later became a mother and remains cancer-free. Avoiding unnecessary chemotherapy also spares patients from side effects such as fatigue, hair loss, infections and potential long-term complications.

Test Is Changing Treatment Decisions

According to Dr Thumsi, recurrence-risk testing sometimes changes treatment plans completely. Some women who appear to have low-risk disease based on conventional clinical factors are found to have biologically aggressive tumours that require chemotherapy. Conversely, patients who appear high-risk because of tumour size or other traditional indicators may actually have a low biological risk of recurrence and can safely avoid chemotherapy. Without recurrence-risk testing, both groups could potentially receive the wrong treatment.

Most of her patients feel relieved when test results show that chemotherapy is unnecessary. At the same time, convincing patients with genuinely high-risk scores to undergo chemotherapy can still be challenging because of their fears.

Barriers to Wider Adoption

Experts believe greater awareness among oncologists and surgeons—particularly in smaller cities and rural areas—is essential to expand access to recurrence-risk testing. Although CanAssist Breast is significantly more affordable than many international alternatives, cost can still be a barrier for some families. Dr Shah notes that avoiding unnecessary chemotherapy not only lowers treatment costs but also reduces hospital visits, treatment-related side effects and the logistical challenges of travelling to specialised cancer centres.

Dr Shah estimates that around 75-80% of eligible women who undergo recurrence-risk testing are classified as low risk and can often safely avoid chemotherapy without compromising their long-term outcomes. He adds that recurrence-risk tests are decision-support tools rather than replacements for clinical judgement. Backed by robust clinical evidence and long-term follow-up studies, they have become an important part of modern breast cancer care. “When used in the right patients and interpreted alongside clinical assessment, these tests allow doctors to personalise treatment while maintaining oncological safety,” he says.

As cancer care moves steadily towards precision medicine, recurrence-risk tests such as CanAssist Breast are helping ensure that treatment is guided not just by how a tumour looks under the microscope, but by how it is likely to behave; allowing many women to avoid unnecessary chemotherapy while ensuring those who truly need it receive timely treatment.

Also read:

1. Obese Women Are Not Only At Higher Risk Of Breast Cancer, But Also Host The Conditions For The Cancer To Become Invasive
2. MP Researcher Develops Smart Drug Delivery System That Targets Breast Cancer Cells Without Chemotherapy Side Effects
3. New IIT BHU Study Finds Potential Alternative To Chemotherapy For Breast Cancer Treatment