Thyroid Cancer Follicular

Follicular cancer generally comprises about 25% of all diagnosed thyroid cancers and is usually a more aggressive form of cancer than the more common papillary type. Similar to papillary cancer, follicular thyroid cancer is most often discovered as a painless lump in the thyroid, usually occurs after the age of 40, and occurs more often in women than in men.

Diagnosis

Unlike papillary thyroid cancer, it can be difficult to diagnose without performing surgery because there are no characteristic changes in the way the thyroid cells look. Rather, the only way to tell if a follicular or Hurthle cell nodule (or neoplasm) is a cancer, is to look at the entire capsule around the nodule and see if there is any sign of invasion. A fine needle aspiration (FNA) biopsy usually cannot distinguish between follicular adenoma (the precursor to follicular cancer), follicular cancer and a completely benign condition called nontoxic nodular goiter. Even a coarse needle biopsy, which is typically more accurate than an FNA, cannot always provide an answer since it is only able to differentiate between a follicular neoplasm (which includes both adenoma and cancer) versus nontoxic nodular goiter about 40% of the time. These biopsies can only look at individual cells and not the entire capsule. This difficulty in diagnosis is one of the most frustrating areas for physicians who study thyroid disease, because it means that surgery is often the only way of definitively diagnosing a thyroid nodule. Patients with a follicular or Hurthle cell neoplasm typically require removal of half of the thyroid gland, called a diagnostic lobectomy. We call this procedure a "diagnostic lobectomy" because we are trying to make a definitive diagnosis by removing the thyroid lobe. The pathologist then looks at the entire capsule around the nodule to see if there is a follicular or Hurthle cell cancer. This elaborate inspection can sometimes take up to a week to perform. Depending on the individual patient and his or her risk factors, up to 80% of patients undergoing diagnostic lobectomy will have a benign nodule and not require further therapy. Unless we definitely know a nodule is a thyroid cancer during the operation or there are nodules in the opposite lobe, we will only remove one half of the thyroid gland, since removing both sides of the thyroid gland is associated with increased complications and there is a good chance you would not need to take thyroid hormone if you have one side of your thyroid remaining. If there is a cancer, the patient will require removal of the other half of the thyroid in an operation called a "completion thyroidectomy."

Treatment

Follicular thyroid cancer can be completely cured by surgery. However, like papillary thyroid cancer, there is controversy about how much thyroid should be removed. Not only is the diagnosis of follicular thyroid cancer difficult to make before an operation, it can be difficult to make during the operation as well. The diagnosis of follicular thyroid cancer is usually only made after the operation, when the pathologist can thoroughly inspect and examine multiple portions of the thyroid nodule under the microscope. Patients with thyroid cancer on the final pathology will require that the rest of their thyroid be removed in an operation called a "completion thyroidectomy." Your surgeon will usually use the same incision and you can expect the recovery to be similar to the recovery after the initial operation. Aggressive follicular cancers can usually be recognized by the surgeon during the first surgery and are best initially treated by total thyroidectomy.

Follow Up

Follow-up and treatment after you have undergone thyroid surgery for follicular carcinoma is similar to that detailed above under papillary thyroid cancer. Unlike papillary cancer however which can metastasize (spread) to the lymph nodes in the neck, follicular cancer tends to spread to different sites such as the lungs or bones.

If metastatic disease affects the bones, for example the spine, it weakens the bones and can cause a fracture. Depending on the location of the metastases, this can have catastrophic effects. For example, if the vertebral column is involved, collapse of these bones could lead to paralysis. Treatment with radioactive iodine or external radiation therapy may be necessary to stabilize the bone and decrease pain from the cancer invasion.

Pathology is key in predicting survival. Tumors with microscopic capsular or venous capsular invasion have cure rates in the 99% range. Cancers that can be recognized by the surgeon have a 10 year cure rate in the 40% range. The Hurthle cell variant of follicular or papillary cancer is of note because they do not concentrate radioactive iodine very well (if at all) and are more likely to metastasize (spread) to other parts of the thyroid and to lymph nodes.