Hormone therapies for patients with hormone receptor-positive tumors are generally highly effective. Hormone (Endocrine) therapyies are most commonly used in cases of breast and prostate carcinomas.
In hormone therapy, receptors on cell surfaces are either blocked (Tamoxifen) or the body’s hormone production (such as estrogen in breast cancer) is reduced (Aromatase inhibitors) to prevent these receptors from being activated.
Behavior of Circulating Tumor Cells During Hormone Blockade
The initial measurement of the maintrac® cell count always serves as a baseline, which, when considered alongside subsequent measurements, provides insights into the course of the disease.
Since the medications used in hormone therapies do not have properties to kill CTCs, the cell count usually remains stable or slightly decreases over an extended period.
Unfortunately, when the hormone blockade is ineffective, we often observe an increase in cell count.
Decreasing Cell Count
In the illustration, you can observe that during Tamoxifen therapy (hormone blockade), the cell count decreases over the years. Not all cells are destroyed; instead, some are temporarily turned into “sleeping” cells (dormancy). Continuing the therapy is advisable to prevent the development of micrometastases.
Constant Cell Count
Bleiben unter der adjuvanten Hormonblockade die Zellzahlen konstant, ist dies eher ein gutes Zeichen. Jahrelang konstante Zellzahlen ist sehr oft mit einer guten Prognose verbunden.
Fluctuating Cell Count
Irregular medication intake can lead to fluctuations in cell count trajectories for patients undergoing antihormonal therapy. Fluctuating cell counts in patients before menopause can also result from inadequate suppression of estrogen production.
Increasing Cell Counts in Hormone Therapies
If the cell count steadily rises over an extended period, this is often attributed to the therapy’s insufficient effectiveness. Experience shows that the treatment should be modified, such as switching from Tamoxifen to Aromatase inhibitors.
Hormone Therapies: When Is it Safe to Stop Hormone Therapy?
The side effects of antihormonal therapy can be quite pronounced. Hence, patients often question the necessity of prolonged antihormonal therapy. Based on numerous maintrac® measurements, there may be indications 8-12 weeks after the completion of hormone therapies about whether continuing the treatment is necessary or if it should be maintained. To address this, a performance evaluation is being conducted in 2023-2024, with the aim of marking maintrac® with the CE mark for medical diagnostics for this specific question.
Cell Count Evolution in Long-Term Monitoring
Decreasing or Constant Cell Count
If the cell count decreases after discontinuing hormone therapy or remains at the same level, this suggests a positive course of the cancer. No tumor activity is evident. Continuing hormone therapies is not strictly necessary, but monitoring the cell count trend is advised.
Increasing Cell Counts
If therapy is terminated and there is a subsequent increase in CTCs shortly afterward (around 6-12 weeks), we recommend resuming antihormonal therapy. Studies in hormone receptor-positive breast cancer patients have established a clear correlation between the increase in cell count after discontinuing hormone treatment and the rate of recurrence (new tumor growth).