A team of scientists have developed an online calculator that doctors can use to help predict the risk of return of certain breast cancers, elsewhere in the body. Late distant recurrence of breast cancer is when the the cancer returns in another part of the body, longer than 5 years after the initial diagnosis.
The online tool has been called Clinical Treatment Score post-5 years (CTS5) and it is designed to help doctors understand hormone-receptor-positive breast cancer. These types of breast cancer can reoccur after 5 years or more in about 50% of cases while most hormone-receptor-negative recurrences of the disease happen within the first 5 years of when a patient is first diagnosed. The study was published in the Journal of Clinical Oncology in July 2018 and can be accessed under a Creative Commons licence. The study was funded by a number of international charities linked with breast cancer.
Patients who have been diagnosed with hormone-receptor-positive breast cancer are offered hormone therapy for 5 years. The best known is possibly Tamoxifen. It can treat both premenopausal and postmenopausal women. Aromatase inhibitors are more often used for postmenopausal women. Studies show that more than 50% of recurrences can occur after that time frame, and some studies have shown that if treatment is extended after 5 years, then the disease outcome could be improved, but there is also a greater risk of adverse side effects. The scientists wanted to develop a tool to identify patients, for which the risk of adverse effects would not be worth it because they were low risk.
When a patient is diagnosed with breast cancer, the doctor takes into account her age, the size of the tumour, the number of lymph nodes that contain cancer and the grade of cancer, when estimating the risk of recurrence of the disease following treatment. The scientists found that the nodal status provided a powerful marker for the risk of recurrence, while the size and grade of the tumour were less important. The researchers noted that some of the studies that referred to the importance of these factors were 40 years old, which could limit their application to current disease and treatments. It was difficult to tell individual risk for patients because of the way the data was presented and the scientists also wanted to be able to examine the differences according to the treatment used.
The Clinical Treatment Score post-5 years (CTS5) was developed using measures taken from most patients when diagnosed and data from the ATAC trial (Arimidex, Tamoxifen, Alone or in Combination) to train the diagnostic tool and the Breast International Group (BIG) to test it. Over 10,000 women were recruited for these studies. The ATAC trial contained women who were older by an average of 3 years than the other trial, and more had node-negative disease, more had grade 3 tumours and less women received chemotherapy when compared to the women in the BIG 1-98 trial. The tumour size was similar between the groups. In the BIG group, significantly lower recurrences occurred.
CTS5 managed to successfully separate the women participants into groups according to whether they had low, intermediate or high risk of late distant recurrence after their 5 years of therapy. 42% of women had low late risk recurrence, so would not benefit from extended therapy versus possible side-effects. The CTS5 calculator tool can be accessed online, but it is only recommended to be used by doctors. A patient accessing the tool should check the results with their doctor.
A patient who has been diagnosed with early-stage, hormone-receptor-positive breast cancer is usually offered at least 5 years of hormone therapy after their surgery. When the five years are finished, then the patient and doctor will discuss whether extending the therapy will benefit that patient in their situation.
Taking the medicine prescribed at the right dose and for the right length of time is key to reducing the risk of recurring breast cancer. If side effects occur, then it is best to talk to the doctor, as there are steps that can be taken to help reduce them if needed. Do not stop the therapy without talking to your doctor.
Dowsett, M., et al., Integration of Clinical Variables for the Prediction of Late Distant Recurrence in Patients with Estrogen-Receptor-Positive Breast Cancer Treated with 5 Years of Endocrine Therapy: CTS5, Journal of Clinical Oncology, July 2018