Salvage radiation is a type of radiation therapy used after initial cancer treatment has been completed. This treatment aims to address cancer that has recurred or persisted in a localized area despite previous efforts to eliminate it. The goal of salvage radiation is to target these cancer cells or localized recurrence, offering another opportunity for disease control.
Understanding Salvage Radiation
Salvage radiation therapy is a “rescue” treatment, administered when cancer reappears or continues to be present following initial, curative-intent therapies like surgery or earlier radiation. Its objective is to eradicate any remaining cancer cells or localized areas of recurrence that were not fully eliminated by the first round of treatment.
This approach differs from adjuvant radiation, which is given preventatively shortly after initial surgery, even if no cancer is detectable, to eliminate microscopic cells and reduce recurrence risk. In contrast, salvage radiation is applied specifically when there is clear evidence of biochemical recurrence, such as a rising prostate-specific antigen (PSA) level after prostate removal surgery.
When Salvage Radiation is Considered
Salvage radiation is considered in specific clinical scenarios and for particular cancer types when there is evidence of localized recurrence. For prostate cancer, it is frequently considered when prostate-specific antigen (PSA) levels begin to rise after a radical prostatectomy, indicating biochemical recurrence. A PSA level of 0.2 ng/mL or higher after surgery is a common trigger for considering salvage radiation therapy. Starting treatment when PSA levels are low, ideally below 1.0 ng/mL, is associated with better outcomes. Studies suggest that very early salvage radiotherapy, initiated at PSA levels between 0.2-0.5 ng/mL, can improve outcomes like biochemical relapse-free survival and metastasis-free survival.
For head and neck cancers, salvage radiation, often combined with surgery or chemotherapy, may be considered for recurrent or second primary cancers in previously irradiated areas. This is particularly relevant when local or regional recurrence occurs, despite initial treatments. The decision often depends on factors such as the time elapsed since the initial radiation, the extent of the recurrence, and the patient’s overall health and ability to tolerate further aggressive treatment.
In cases of locally recurrent rectal cancer, salvage radiation can be an option, especially when surgical removal is not feasible due to tumor extension or fixation to pelvic structures. Reirradiation, or secondary radiation, may be offered, and dose-escalated radiation, 70 Gy or more, has shown a benefit in reducing the risk of progression.
The Salvage Radiation Process
The salvage radiation process begins with a thorough diagnostic workup to confirm the recurrence and pinpoint its precise location. This often involves advanced imaging techniques such as PET scans, CT scans, bone scans, or specialized MRIs, which help identify the exact site of cancer cells that require treatment. For prostate cancer, prostate-specific membrane antigen (PSMA) PET/CT scans are used to detect local recurrence and guide treatment planning.
Once the recurrence is confirmed and localized, the treatment planning phase commences. This involves a simulation to create a detailed map of the treatment area and surrounding healthy tissues. Dosimetry calculations are performed to determine the precise radiation dose distribution, ensuring that the target receives an adequate dose while minimizing exposure to nearby organs. Advanced techniques like Intensity-Modulated Radiation Therapy (IMRT) or Stereotactic Body Radiation Therapy (SBRT) are used to deliver highly focused radiation. IMRT shapes radiation beams to conform to the tumor’s irregular shape, while SBRT delivers high doses in fewer sessions due to its improved targeting accuracy.
The duration and frequency of salvage radiation treatment sessions can vary depending on the cancer type and specific technique. For prostate cancer, radiation is often administered five days per week, over a period of four to eight weeks. In some cases, hormone therapy, such as androgen deprivation therapy (ADT), may be given concurrently with salvage radiation to enhance its effectiveness.
Post-Treatment Outlook and Monitoring
After completing salvage radiation, patients can expect a period of recovery, during which some common short-term side effects may manifest. These can include urinary issues like increased urgency, frequency, or painful urination, and bowel issues such as loose stools, diarrhea, or a burning sensation in the rectum. Erectile dysfunction is also a potential side effect. Most short-term side effects are mild to moderate and often resolve within a few weeks after treatment concludes.
Ongoing monitoring is a significant aspect of post-treatment care to track the treatment’s impact and detect any further changes. Regular follow-up appointments with the oncology team are scheduled. For prostate cancer, monitoring prostate-specific antigen (PSA) levels is standard. After salvage radiation, the PSA level should slowly decline, ideally to less than 0.05 ng/mL, indicating effective treatment. If the PSA level remains above 0.1 or 0.2 ng/mL, it may suggest persistent cancer.
While many side effects are temporary, some patients may experience long-term effects. These can include persistent urinary or bowel dysfunction, or ongoing sexual issues. Open communication with the healthcare team is encouraged to promptly report any new or worsening symptoms, ensuring appropriate and timely medical attention and management of any potential long-term effects.