CHAPTER 19: RECURRENT OR PERSISTENT DISEASE AFTER TREATMENT, AND THE NEED FOR FOLLOW-UP
A recurrent lesion is one that regrows after apparently successful treatment, that is, where the neurosurgeon thought that the lesion was obliterated by the procedure. On the other hand, a persistent lesion is one that continues to grow because the neurosurgeon was aware that it was not completely obliterated at the initial treatment attempt. Why wasn’t it obliterated completely? The lesion may have been too large or too deep for the attempted treatment, or may have been too close to, or involving, a critical brain neurovascular structure. Finally, a new lesion is one that occurs in a different location to any other that was known and treated.
The chance of the same lesion recurring or regrowing after treatment really depends on two critical factors: (1) The extent of surgical resection; and (2) the pathology of the lesion. The former refers to how much of the lesion was physically removed or resected by the surgeon, while the latter refers to the exact type of lesion itself based on a pathologist’s microscopic look at the cells making up the lesion.
Consider the following examples:
· Brain aneurysm: The chance of the same brain aneurysm growing is significantly higher if an endovascular surgeon or microneurosurgeon could not fully obliterate the aneurysm, that is, left a small corner or “dog ear” for whatever reason. In such situations, the chance of detecting ongoing growth in that aneurysm is around 1% per year. For endovascular treatment of larger aneurysms, that is, > 10 mm in diameter, the chance of the same aneurysm recurring or regrowing is somewhere between 25-50%, depending on the aneurysm’s original size, and regardless of how well the endovascular treatment seemed to have gone. Of these aneurysms, about half can be effectively re-coiled, but the other half cannot. The latter are more frequently being referred to microneurosurgeons for treatment.
· Benign brain tumor: A benign brain tumor such as a meningioma is not expected to recur if it is entirely removed, that is, gross totally resected, along with the dura from which it arose. If the dura was left behind, or a small portion of tumor was left because it encased a critical blood vessel, the meningioma may certainly grow back. Frequently, this growth or regrowth is slow and can often be significantly retarded or stopped with SRS.
· Malignant brain tumor: A brain tumor such as a World Health Organization (WHO) grade 2, 3, or 4 astrocytoma is expected to recur even despite what appears to be a good resection based on the surgeon’s intraoperative impression and the immediate postoperative MRI. The reason for this is that such tumors do not have distinct borders, and send small fingers of cells deeper throughout the neighboring brain. It is not possible at this time to remove every cell of an astrocytoma, although its growth or regrowth can be significantly slowed by a good resection followed by, where deemed appropriate, radiation therapy and chemotherapy. A high-grade astrocytoma such as anaplastic astrocytoma (WHO Grade 3 of 4) or gliobastoma multiforme (GBM; WHO Grade 4 of 4) is likely to grow or regrow more rapidly than a low-grade astrocytoma (WHO Grade 2 of 4). Untreated GBMs are thought to have overall size-doubling times of approximately one month, and despite multimodality treatment including surgery, radiation, and chemotherapy, have average survival times of approximately 12-15 months.
· Chronic subdural hematoma (SDH): A chronic SDH is a blood clot that has been sitting on the surface of a patient’s brain for weeks or months. Such lesions develop membranes around them, and may have internal walls or loculations. They are notorious among neurosurgeons for being tricky to treat, and are commonly found to be persistent or recurrent despite surgical treatment.
It cannot be overstated that for all of the above reasons and scenarios, it is important that patients with brain conditions have appropriate clinical and radiological followup after treatment of the lesion. This means periodically scheduled Office visits with a physician, and surveillance imaging with, say, head CT or MRI/MRA. This issue should be discussed between the patient and physician prior to dismissal from hospital. Patients can certainly monitor their own symptom progression, and should report significant changes in their neurological state to their doctor.
Just because a patient has recurrent or persistent disease does not mean that there are no further treatment options. Certainly, some patients may be advised against further treatment, owing to, say, the extensive nature of their original disease, poor overall medical condition, or previous “maximal” therapy involving previous surgery, radiation and chemotherapy. However, others do have the options of, for example, repeat surgery and/or SRS where appropriate. For many patients, SRS can be used even if WBRT has been administered. Salvage surgery is a term that is sometimes used in the setting of a patient requiring repeated surgery for an advanced disease process. Some patients undergoing “salvage” treatments fare well, but others do not, despite heroic attempts by all concerned.
