Chemotherapy is intended to kill cancer cells. The timing of the therapy determines whether it is adjuvant or neoadjuvant chemotherapy. Adjuvant chemotherapy is delivered after surgical removal of the tumor. Surgeons remove the entire tumor and a small portion of healthy, neighboring tissue to ensure all cancerous cells have been removed. It is impossible to know for certain whether any stray cancer cells remain after surgery, or whether the tumor had begun to metastasize, or spread, undetected to other tissues. Adjuvant chemotherapy may be thought of as a means of sweeping any lingering cancer cells from the body to prevent recurrence. Adjuvant chemotherapy is used to prevent recurrence of a cancer that may have been completely removed during surgery, so it is difficult to determine if the therapy is effective. After the course of treatment ends, patients are closely monitored for the appearance of symptoms suggesting a return of the cancer.
Neoadjuvant chemotherapy is delivered before surgery to shrink the tumor. Reducing the tumor size prior to surgery makes it easier for the surgeon to remove the tumor with less damage to surrounding tissue. Neoadjuvant chemotherapy also enables the surgeon to better differentiate the edge of the tumor from healthy tissue. As cancer metastasizes, it causes inflammation in neighboring tissue. Neoadjuvant chemotherapy reduces this inflammation and allows more of the healthy tissue to remain. Patients may receive both neoadjuvant and adjuvant chemotherapy.
The timing of delivery of adjuvant chemotherapy versus neoadjuvant chemotherapy is much different. Neoadjuvant chemotherapy is delivered before surgery, with sufficient time allowed for the patient to recover his strength prior to the procedure. Adjuvant chemotherapy is delivered between 2 to 8 weeks after surgery. The patient is given enough time to heal from the procedure. For both adjuvant and neoadjuvant chemotherapy, the duration of treatment depends on the type of cancer, the stage of the cancer, and the patient’s overall health.
Not all cancers respond to chemotherapy and thus are not good candidates for adjuvant or neoadjuvant treatment. Adjuvant chemotherapy in particular requires careful consideration of the type of cancer, whether the cancer has already spread to lymph nodes or neighboring tissue, and the patient’s general health. Slight benefits may not be worth the side effects associated with chemotherapy. Similarly, neoadjuvant chemotherapy is only used for tumors that respond to treatment. Adjuvant therapy is used most often for breast, testicular and ovarian cancers, although it is used in others. Neoadjuvant chemotherapy is most often shrink breast, colorectal, and lung tumors.
Adjuvant and neoadjuvant chemotherapy are associated with the same side effects. Most common side effects include nausea and vomiting, fatigue, hair loss, infection, mouth sores, anemia, and an increased risk of bleeding.
ChemoCare.com: Chemotherapy Terms https://www.chemocare.com/whatis/important_chemotherapy_terms.asp
CancerGuide: Adjuvant Chemotherapy https://cancerguide.org/adjuvant.html
MayoClinic.com: Adjuvant Chemotherapy: When is it Used? https://www.mayoclinic.com/health/adjuvant-chemotherapy/MY00637
Chemotherapy Facts: What Is Neoadjuvant Chemotherapy? https://www.chemotherapyfacts.com/neoadjuvant-chemotherapy.html