A diagnosis of seminal vesicle invasion (SVI) means that cancer cells from the prostate gland have grown into the neighboring seminal vesicles. These two small glands are located behind the prostate and contribute fluid to semen. For the diagnosis to be classified as SVI, the cancer must penetrate the muscular wall of these structures. This finding signifies that the cancer is no longer confined within the prostate gland.
This diagnosis indicates a more advanced stage of the disease, which can be a source of concern. This article explains what SVI means for cancer staging and prognosis, outlines common treatment approaches, and discusses how side effects are managed.
The Significance of Seminal Vesicle Invasion
Seminal vesicle invasion is a form of extraprostatic extension, meaning the tumor has breached the confines of the prostate capsule. This finding directly influences how the cancer is staged and, consequently, how it is treated. SVI may be discovered through imaging like a multiparametric MRI (mpMRI) before treatment or, more definitively, by a pathologist examining tissue after a radical prostatectomy.
In the TNM staging system, SVI classifies the prostate cancer as stage T3b, which is considered “locally advanced.” This is different from “metastatic” cancer. Locally advanced means the cancer has grown into adjacent tissues, while metastatic disease involves the spread of cancer to distant parts of the body, like bones or remote lymph nodes.
This distinction affects the prognosis and treatment strategy. While SVI indicates more aggressive cancer than organ-confined disease, it has not yet spread to distant sites. Treatment for locally advanced cancer aims to control the tumor within the pelvis and prevent further spread, often requiring more comprehensive strategies.
Prognosis and Associated Risk Factors
The presence of SVI directly impacts a patient’s prognosis by increasing the likelihood of the cancer returning after treatment. This return is often measured as a biochemical recurrence, which is a rise in prostate-specific antigen (PSA) levels. However, SVI is just one factor that informs the overall outlook.
A complete risk profile considers SVI along with other pathological details. The Gleason score, which grades cancer cell aggressiveness based on microscopic appearance, is a primary factor. A higher Gleason score combined with SVI points to a higher risk of recurrence.
Other factors in determining prognosis include the patient’s PSA level at diagnosis. After surgery, the status of the surgical margins—whether cancer cells are found at the edge of the removed tissue—is also evaluated. Whether cancer has spread to nearby pelvic lymph nodes is also taken into account. These elements allow doctors to stratify patients into risk groups and tailor long-term plans.
Treatment Approaches for Locally Advanced Prostate Cancer
When prostate cancer has reached the seminal vesicles, a single treatment method is often insufficient. The standard of care for this locally advanced stage involves a multimodal approach, combining therapies to address the cancer in the prostate and surrounding tissues. This improves cancer control and reduces the risk of recurrence.
A primary treatment strategy combines external beam radiation therapy with androgen deprivation therapy (ADT). Radiation uses high-energy rays to destroy cancer cells in the prostate, seminal vesicles, and sometimes pelvic lymph nodes. ADT, or hormone therapy, lowers the levels of male hormones (androgens) that fuel prostate cancer growth. This combination is more effective than either treatment alone for this stage.
Another pathway is a radical prostatectomy, a surgery to remove the prostate and seminal vesicles. If SVI is found after surgery, additional treatments, known as adjuvant therapy, are often recommended. Adjuvant therapy may include radiation to the surgical area or hormone therapy to reduce the risk of the cancer returning.
Managing Treatment Side Effects and Long-Term Follow-Up
Treatments for locally advanced prostate cancer can cause side effects. Common issues from radiation, surgery, and hormone therapy include:
- Urinary problems, such as incontinence or difficulty urinating
- Erectile dysfunction
- Fatigue
- Hot flashes
- A decrease in bone density over time
Urinary problems can be improved with pelvic floor physical therapy and medications, while erectile dysfunction can be treated with oral medications and other options. Side effects from hormone therapy can be managed through regular exercise to combat fatigue and maintain muscle, along with medications to protect bone health.
Long-term follow-up involves regular PSA tests to monitor for the cancer’s return. A rising PSA level after treatment is called a biochemical recurrence and may indicate that cancer cells have survived. If this occurs, further treatments, known as salvage therapies, can be used to control the cancer.