ENDOCRINE TUMORS Flashcards
What is the epidemiology of thyroid cancer?
- Thyroid cancer being 94% of all new endocrine cases, but represent only 2% of all cancer types.
- F»_space; M
- 25 to 65 years old
What are the etiological factors for thyroid cancer?
- External Radiation, particularly before puberty. Back in the 1930s and on, external radiation was given to trear acne, tonsilitis, therefore radiation was given at early age.
- Iodine defficiency
- Genetic factor
- Long standing history of goiter (due to hyperthyroidism)
What are the prognostic factors for thyroid cancer?
- Age
- Gender
- Histologic subtype
- NOT LYMPH NODE INVOLVEMENT
What are the 4 lymphatic capillaries arranged throughout the thyroid gland?
- Internal jugular chain
- Delphian (anterior cervical) node
- Pretracheal nodes
- Paratracheal nodes
What are the two principal hormones produced by the thyroid gland?
- Thyroxine (T4)
- Triiodothyronine (T3)
Both are responsible of metabolic regulation.
What are the functional disorders of the thyroid gland characterized by hyperthyroidism?
- Grave’s disease, characterized by elevated metabolic rate, abnormal weight loss and exophthalmos (proptosis)
- Goiter, sign of enlarged thyroid gland, overstimulation by TSH associated with increased hormone production and toxic goiter.
What are the functional disorders of the thyroid gland characterized by hyporthyroidism?
- Cretinism, abnormal bone formation, retarded mental development
- Myxedema, swollen tissues caused by excess body fluid.
What are the most common clinical presentation for thyroid cancer?
- Palpable neck mass, detected during routine physical examination
- Asymptomatic painless mass (medullary carcinoma)
- Pain, dysphagia, dyspnea, stridor hoarseness (anaplastic carcinoma)
What are the Detection tools for thyroid cancer?
- Biopsy (the most important)
- CT
- MRI
- Radionuclide thyroid imaging
- Sonography (ultrasound), can determine solid vs. cystic thyroid nodule
- Needle biopsy, needle aspiration or core-needle biopsy with 10% false-positive incidence
What are the 4 most common radiopharmaceuticals used in radionuclide imaging for thyroid cancer?
- Iodine-131
- Iodine-125
- Technetium-99m
What are the three ways a thyroid nodule can appear on a radionuclide thyroid imaging?
- cold thyroid nodule (no radionuclide uptake)
- warm thyroid nodule (slightly higher concentration than rest of thyroid gland)
- hot thyroid nodule (radionuclide uptake much higher than rest of thyroid gland)
What is the most common histopathology for thyroid cancer?
Well-differentiated carcinoma:
-papillary and mixed-papillary-follicular (33-73%)
-follicular (14-33%)
-medullary (5-10%)
Undifferentiated carcinoma:
-anaplastic carcinoma(10%), worst prognosis
Iodine-131 and thyroid hormone suppression treatments given for papillary and mixed papillary-follicular and follicular
What are the common spread routes for the different histopathology in thyroid cancer?
- Papillary and medullary carcinoma = through regional lymph nodes
- Follicular carcinoma = hematogenously
- Anaplastic = invasion locally to trachea
What is the most common site of distant METS for thyroid cancer?
Lungs
What is the common lymph node spread for thyroid cancer?
- Para-laryngeal
- Para-tracheal
- Pre-laryngeal
secondary METS: mid to lower jugular nodes and supraclavicular
What is the treatment of choice for thyroid cancer?
- Surgery (primary approach) thyroidectomy
- Iodine-131 (Nuclear Medicine)
- Hormone therapy, thyroid hormone suppression
- Radiation Therapy
Rx + or - I-131
What are the side effects of Iodine-131 therapy?
- Inflammation of salivary glands
- Nausea
- Vomiting
- Fatigue
- Bone Marrow suppression (after repeated administrations)
What is the rationale of Thyroid Hormonal therapy for thyroid cancer?
-Differentiated thyroid carcinomas grow by TSH stimulation, therefore if we reduce the TSH levels, the tumor activity should also decrease.
What is the rationale of Radiation Therapy for thyroid cancer?
Radiation Therapy:
The responsiveness to Rx varies according to the histological type.
Papillary and mixed papillary-follicular = RADIOSENSTIVE
Follicular and medullary is more resistant than above
Anaplastic is not very responsive to Rx.
What is a typical Rx treatment dosage for thyroid cancer?
- 65 Gy / 7 weeks , AP/PA or now IMRT, CURATIVE
- 35 to 45 Gy / 3 to 5 weeks, BONE METS INVOLVEMENT
Target Volume: entire thyroid, neck and superior mediastinum
What is required to be out of the field when simulating a thyroid cancer patient?
The ORAL CAVITY, needs to be out of field by extending the head (using the appropriate head rest on U-frame)
What is Grave’s disease?
a disease resulting from an overactive thyroid gland, causing toxic goiter, it;s a type of hyperthyroidism
-Exophthalmos and dry eye feeling
-Antibodies bind to surface of thyroid cells and stimulate them to overproduce thyroid hormones
What is the epidemiology/etiology of Grave’s disease?
- M
- middle age
- genetic predisposition
- infections or stress related
What are the clinical symptoms of Grave’s disease?
- Fatigue
- Weight loss
- Restlessness
What is Pterygium?
- A benign disease (non-cancerous), pinkish, triangular-shaped tissue growth on the cornea
- slowly growing and rarely cover the pupil of the eye
What is the epidemiology/etiology for Pterygium?
- affects 20-50 years old
- UV exposure and dust
What is the treatment of choice for Pterygium?
- Surgery excision + Radiation (post-operative)
- Recurrence 20-30% if not given with Rx, <2% if given with Rx.
- Rx given usually within 48 hours post-operative
What element is used to treat Pterygium?
Strontium-90 for Rx T1/2 = 28.1 years 0.54 MeV Dose rapidly attenuated at 2mm = 38% of dose at 4 mm = 10% of dose
What is a typical dose to treat Pterygium with Rx?
- 18 Gy / 1 fx
- 60 Gy / 10 fx
- 24 Gy / 3 fx (0-7-14)
