Androgen Deprivation Therapy, or ADT, is a form of hormone treatment for prostate cancer. Its function is to lower the body’s levels of androgens, which are male hormones like testosterone. Prostate cancer cells often use these hormones to grow, so reducing the available androgens with ADT can slow the cancer’s progression. This treatment is a primary approach for managing the disease, particularly in its more advanced stages.
Duration of ADT Effectiveness
The length of time Androgen Deprivation Therapy remains effective is tied to the specific stage of the prostate cancer. For individuals with cancer that is localized or has spread only to nearby tissues, ADT is used for a predetermined duration. This period ranges from six months to three years and is often combined with other therapies, such as radiation, to improve the likelihood of a successful outcome.
When dealing with metastatic hormone-sensitive prostate cancer (mHSPC), where the cancer has spread to distant parts of the body but still responds to hormonal manipulation, ADT is a primary treatment. The therapy can remain effective for several years, though this timeframe varies significantly from person to person. While an average duration is two to three years, many individuals experience control for much longer.
The variability in ADT’s effectiveness is influenced by several biological factors present at diagnosis. The aggressiveness of the cancer, measured by a Gleason score, and the extent of the disease also impact the duration of the therapy’s efficacy.
When ADT Is No Longer Sufficient
Over time, prostate cancer cells can change in a way that allows them to grow even when androgen levels in the body are very low. This development marks a shift in the disease, which is then identified as castration-resistant prostate cancer, or CRPC. The term “castration-resistant” refers to the fact that the cancer is progressing despite the therapy maintaining testosterone at or below castration levels.
The emergence of CRPC does not mean the initial treatment has failed, but signals a biological adaptation by the cancer cells. These cells have found new pathways to fuel their growth that are not dependent on the high levels of testosterone they once required. For this reason, ADT is often continued because it still provides a benefit by suppressing the remaining sensitive cancer cells.
This transition to CRPC is a documented phase in the progression of advanced prostate cancer. It represents a change in the biology of the tumor, as the cancer cells rewire their internal signaling to bypass the blockade created by ADT.
Treatment Schedules For ADT
The administration of Androgen Deprivation Therapy can follow different schedules depending on the individual’s situation and treatment goals. One approach is continuous ADT, where the therapy is administered without any planned interruptions. This method ensures that androgen levels remain consistently suppressed over the long term.
An alternative method is intermittent ADT, which involves giving the treatment in cycles. With this approach, therapy is administered until the patient’s prostate-specific antigen (PSA) level drops to a low, stable point. Treatment is then paused and only restarted when the PSA level begins to rise again, indicating renewed cancer activity.
The primary reason for using an intermittent schedule is to help manage the side effects associated with long-term hormone suppression. By providing planned breaks from the therapy, patients may experience an improved quality of life. Some studies also suggest this cyclical approach could delay the development of resistance to the therapy.
Treatment Options After Initial ADT Efficacy Wanes
When prostate cancer advances to the castration-resistant stage (CRPC), the initial ADT is no longer sufficient on its own, and the treatment strategy evolves. At this point, several advanced therapeutic options become available to continue managing the disease. These treatments target the new mechanisms the cancer cells are using to survive in a low-androgen environment.
One major class of next-step treatments is second-generation anti-androgens. Drugs like abiraterone acetate and enzalutamide work by targeting the androgen-signaling pathway in more sophisticated ways. Abiraterone blocks the production of androgens throughout the body, while enzalutamide directly inhibits the androgen receptor from signaling cancer cells to grow.
Should the cancer continue to progress, other types of therapies may be introduced. These options include chemotherapy with drugs such as docetaxel, immunotherapy, which helps the body’s own immune system fight the cancer, and targeted therapies that interfere with specific molecules involved in cancer cell growth.