Unresectable Cancer Reasons and Exceptions

Unresectable cancer is defined as a cancer or tumor that cannot be removed completely through surgery. Since surgery often offers the best chance for a cure with solid tumors, this can be discouraging news to hear.

Yet just because a tumor is inoperable does not mean it is untreatable. It's also important to note that with advances in cancer research, not all tumors that are initially unresectable will remain inoperable indefinitely. 

Serious surgeon talking with senior patient lying on bed in hospital ward
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Reasons a Tumor May Be Unresectable

A tumor may be unresectable for several reasons. Some of these include:

  • The size of the tumor: The tumor may be too large to safely remove, or may require removing too much of an essential organ for surgery to be feasible.
  • The location of the tumor:  A tumor may be intertwined with blood vessels and other vital structures in the body making safe removal impossible.
  • Spread of the tumor to distant sites (metastases): Since metastatic cancer (stage 4 cancer) has spread to regions beyond the tumor, removal of the tumor will not control all of the cancer. In certain other cancers, the involvement of specific lymph nodes may also take resection away as a possibility. Surgery and radiation therapy are considered local treatments, they treat only the area where a tumor is and a small amount of surrounding tissue. In contrast, chemotherapy, hormonal therapies, targeted therapy, and immunotherapy are systemic treatments—they treat cancer cells that are located anywhere in the body (an exception is that some chemotherapy and other drugs do not readily pass through the blood-brain barrier making treatment of brain metastases difficult).
  • Other health conditions that could raise the risk of surgery: Such as heart disease, lung disease, or severe diabetes that would raise the risk of surgery to unacceptable levels.


It's important to keep in mind that just because a tumor is unresectable does not mean it is untreatable. Systemic treatments—treatments that treat the whole body rather than just the site of cancer—may extend life and improve symptoms for many people living with cancer.

While we tend to associate surgery with the ability to "cure" cancer, some of the newer systemic treatments may offer a chance for longer-term survival. Examples of this with lung cancer include newer radiation technologies, immunotherapy medications, and targeted therapies with the option of switching to another targeted therapy when a tumor becomes resistant. In fact, the survival rates for many advanced cancers are improving due to these options.

Exceptions to the Rule

While it was thought at one time that unresectable meant permanently unresectable, this thought is changing. A review of the literature to date reveals many examples of solid tumors such as non-small cell lung cancer, colorectal cancer with liver metastases, bladder cancer, exocrine pancreatic cancer, advanced melanoma, and more, in which aggressive treatment with chemotherapy and sometimes radiation therapy (called neoadjuvant therapy or downsizing) reduced the size of a tumor to the point in which surgery was possible; tumors that were unresectable initially became resectable.

It's important to note, however, that there are many factors that go into making this a true possibility, and each case varies. Discuss your personal options with your physician.

The Concept of Oligometastases

Another new and refreshing concept in what was once unresectable cancer is the concept of oligometastases. The term oligo means few, and what this describes is a solid tumor that has one or only a few areas to which it has metastasized. By definition metastatic cancer or stage 4 cancer would be considered inoperable; surgery would be unable to treat all of the tumors. The thought has been that surgery would be an unneeded discomfort and risk if it would not really make a difference in the course of the tumor. (Note, there are some exceptions to this rule, for example in ovarian cancer partial surgery (cytoreduction) or "debulking surgery" may be considered to lengthen life.) 

An example of treatment using this approach would be treating what was once considered inoperable non-small cell lung cancer in a patient with lung cancer plus one or a few brain metastases. There have now been people who have had surgery for both their lung cancer and to remove one or a few brain metastases who have achieved long-term survival, though again success in this area depends on a case-by-case basis.

A Word From Verywell

If you've heard that your tumor is unresectable, you are probably feeling discouraged, but keep in mind that unresectable cancers are still treatable. While not usually curable (with some exceptions,) treatments such as chemotherapy, targeted therapies, hormonal therapy, and immunotherapy can often extend life, reduce symptoms, and have, for some people, resulted in long term control of their disease (referred to as a durable response by oncologists.)

Being diagnosed with unresectable cancer does not always mean that a cancer will never be operable. Some cancers respond to treatments such as chemotherapy and radiation therapy and are reduced in size so that surgery may later be possible. Be sure to speak openly with your physician about the risks, benefits, and side effects associated with various treatment plans to determine the best option for you.

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