The terms “adjuvant therapy” and “neoadjuvant therapy” do not refer to a specific cancer medication or treatment. Rather, they refer to the timing of therapies within an overall treatment regime.

Both adjuvant and neoadjuvant therapies may encompass chemotherapy, radiation therapy, hormone therapy, and others.

Neoadjuvant therapy occurs prior to someone’s primary cancer treatment. Adjuvant therapy occurs after. For example, an individual may have surgery to remove a tumor, followed by adjuvant chemotherapy.

Read more to learn about adjuvant and neoadjuvant therapies, their uses, benefits, and side effects.

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Neoadjuvant therapy includes treatments that doctors use as an initial step to shrink tumors and kill any cancer cells that have spread. After that, they will start the primary treatment.

Types of neoadjuvant therapy include:

  • radiation therapy
  • chemotherapy
  • hormone therapy

Adjuvant therapy is any treatment that doctors administer following the primary treatment. For example, when doctors use adjuvant therapy to treat people with cancer, it reduces the risk of cancer returning.

Treatments doctors use for adjuvant therapy include:

  • chemotherapy
  • radiation therapy
  • targeted therapy
  • hormone therapy
  • biological therapy

Doctors may use adjuvant therapies in people with early stage cancer who have had surgery as their primary treatment. For example, they may use adjuvant chemotherapy to address cancer cells that remain after surgery or that have spread.

There is considerable overlap in adjuvant and neoadjuvant treatment options. The primary difference is their timing in the overall treatment schedule.

Doctors plan a treatment schedule depending on the individual and the type and stage of cancer. For example, they may use neoadjuvant therapy to shrink a tumor and improve the success of the surgery. They may then follow this with adjuvant therapy to destroy any remaining cancer cells, reducing the risk of recurrence.

They may also recommend neoadjuvant therapy to shrink large tumors before surgery. This can increase the surgery’s chances of success and make the procedure less invasive.

In some cases, doctors prefer neoadjuvant therapy because it allows them to see how the cancer responds to treatment right away. They can then make adjustments for future treatment protocols. It may also give people extra time to seek genetic testing or plan reconstructive surgery prior to more aggressive treatment methods.

Doctors may prescribe both neoadjuvant and adjuvant therapies.

While doctors can use neoadjuvant and adjuvant therapies to treat any type of cancer, they commonly use them to treat breast, lung, and colon cancers.

Doctors use these additional therapies to ensure all cancer cells are targeted, including those that do not show up on scans and those that have spread to distant parts of the body.

With breast cancer, neoadjuvant chemotherapy often aims to shrink the tumor enough to avoid needing a mastectomy. A 2017 study analyzed how effective it was in doing this, and researchers found that it could reduce mastectomy rates by 7–13%.

When treating breast or prostate cancer, doctors may use endocrine or hormone therapy as a form of neoadjuvant therapy.

Conditions that impact someone’s recommendation for adjuvant or neoadjuvant therapy may include:

  • the cancer type and stage
  • the goal of treatment, such as slowing tumor growth or easing symptoms
  • how far the cancer has progressed
  • the general health of the individual

Both therapies offer various benefits to people living with cancer.

Neoadjuvant therapies can:

  • shrink tumors, making their surgical removal more straightforward
  • make inoperable tumors operable
  • reduce the need for mastectomies
  • kill any cells that have spread

A 2015 review noted that neoadjuvant therapy could increase the likelihood of survival for people with certain cancers.

Adjuvant therapy can improve a person’s long-term outcomes. For people with cancer that has spread, it can reduce the likelihood of recurrence.

Despite the benefits that neoadjuvant and adjuvant therapies can offer those living with cancer, individuals must consider the potential side effects for the following:

  • Chemotherapy: Common side effects include nausea, fatigue, infections, anemia, and hair loss.
  • General radiation: Early, short-term side effects include fatigue, skin irritation, and hair loss.
  • Hormone therapy: Side effects can include hot flashes, fatigue, memory problems, and decreased sexual desire.

When deciding on a course of treatment, both the doctor and individual must carefully consider if the expected benefits outweigh any potential risk of side effects.

Doctors most commonly use chemotherapy as adjuvant or neoadjuvant therapy. Chemotherapy agents are powerful drugs that kill or slow the growth of cancer cells.

Some examples of chemotherapy drugs that doctors use for adjuvant and neoadjuvant therapies include:

  • anthracyclines, including doxorubicin (Adriamycin) and epirubicin (Ellence)
  • 5-fluorouracil (5-FU) or capecitabine (Xeloda)
  • taxanes, including paclitaxel (Taxol) and docetaxel (Taxotere)
  • carboplatin (Paraplatin)

Neoadjuvant and adjuvant therapies can include chemotherapy, radiation, and hormone therapy.

If doctors deliver the therapy before the primary treatment, they refer to this as neoadjuvant therapy. This therapy aims to shrink tumors and kill any cancer cells that have spread from the primary site.

Adjuvant therapy follows the primary treatment and helps reduce the risk of cancer recurring.