ADJUVANT THERAPY FOR DTC

1. Radioactive iodine therapy
for DTC
Dept of Surgical oncology
TNGMSSH, Chennai
Prof MP Vishwanathan Ms MCh
Prof D Suresh kumar MS,DNB, MCh, DNB
Presenter : Dr. ARVIND RAJ
MCh PG
Surgical oncology

2. ADJUVANT TREATMENT IN DTC
The mainstay of adjuvant treatment for dtc
--Radioactive 131i treatment
-- Tsh suppression

4. POST-OPERATIVE RISK STRATIFICATION FOR RISK OF
STRUCTURAL DISEASE RECURRENCE
Low-risk patient
• No regional or distant metastases
• No macroscopic residual tumours after resected(r0 / r1)
• No extrathyroid extension
• No tumour aggressive histology (tall cell or columnar cell ptc, diffuse sclerosing
ptc, poorly differentiated elements)
• No angioinvasion.
• Ln <_5 micrometastasis(<.2cm)
NO I 131 THERAPY

5. INTERMEDIATE-RISK PATIENTS
• Microscopic extrathyroidal extension (t3)
• >5 ln (0.2-3cm) (n1a or n1b)
• Vascular invasion
• Tumour with aggressive histology
Tall cell or columnar cell ptc
Diffuse sclerosing ptc
Poorly differentiated elements
Angioinvasion
PROBABLE I131THERAPY Consider on individual case

7. HIGH-RISK PATIENTS
• Gross extrathyroidal invasion
• Incomplete macroscopic tumour resection (r2)
• Distant metastases (m1)
• Node >3cm/ene
• INAPPROPRIATELY HIGH POST OP tg LEVEL
DEFINITIVE 131I THERAPY

8. AIMS OF POST-OPERATIVE I131 TREATMENT

9. FACTORS AFFECTS SUCCESS OF RAI THERAPY
• Histology of the tumor
• Age of the patient
• Size of lesion
• Lymph nodal status
• Distant metastases
• Patient preparation prior to therapy

10. RADIOIODINE 123I,131I
• 123I -- imaging
• I31I -- ablation & therapy
Half life - 8 days
It emits = beta particle--therapy
=Gamma --imaging

11. PATIENT PREPARATION PRIOR TO 131I IMAGING OR
THERAPY
• Pregnancy should be excluded
• Thyroid hormone(Lt4) withdrawal (3 to 6 weeks) prior
• Weaned off from stable iodine-containing foods & drugs (I.v contrast,
Amiodarane, Fish oil,sea food, diary products, MVT tablets)-10- 14 days
prior
• Contrast Administration if done CT requires 2 months for complete washout
• Desired TSH level to proceed with 131I treatment (TSH > 30 μIU/ml)
• serum thyroglobulin (tg) should be checked in this hypothyroidism state at
>6wks of pod

12. Use of Recombinant TSH
ATA- recommendations
In patients with ATA low-risk and ATA intermediate risk DTC without extensive lymph node
involvement , in whom RAI remnant ablation or adjuvant therapy is planned, preparation with
rhTSH stimulation is an acceptable alternative to thyroid hormone withdrawal for achieving
remnant ablation, based on evidence of superior short-term quality of life, noninferiority of
remnant ablation efficacy, and multiple consistent observations suggesting no significant
difference in long-term outcomes.
Rh TSH reduce the risk of hypothyroid-related complications in patients with significant medical
or psychiatric comorbidity .
Not FDA approved for metastatic disease

13. USE OF rhTSH-ASSISTED THERAPY
PATIENTS WHO ARE AT SIGNIFICANT RISK FOR SIDE EFFECTS FROM
HYPOTHYROIDISM
• Elderly / frail patient
• Cardiac patients / severe angina
• Spine or brain metastases
• Central hypothyroidism / hypopituitarism,
• Functional metastases (suppressing tsh)
• History of psychiatric disturbance from hypothyroidism.
RECOMBINANT TSH PROTOCOL: 2 doses given i.m on Day1 & Day 2. RadioIodine is
given on Day 3. Suppresive dose of thyroxine started 3 days after therapy with
normal diet

14. DIAGNOSTIC SCINTIGRAPHY
• Initial diagnostic whole-body scan should be done 3–4 weeks after total
thyroidectomy
• 123I OR 131I (Low dose 1 to 3 mci)
• 123I is more commonly used in imaging techniques - reducing tumor stunning
effect.
Scan helps in
 -Staging
 -Indication
 -Dosing of 131I therapy

15. 131I THERAPY DOSE –ATA guidelines
Fixed dose or dosimetry method.
Conventionally, fixed dose is favoured-one time dose
• 30 mci- ablation ATA low-risk thyroid cancer or intermediate-risk disease
with lower risk features
• 150 mci--When RAI is intended for initial adjuvant therapy to treat
suspected microscopic residual disease, administered activities above those
used for remnant ablation up to 150mCi are generally recommended (in
absence of known distant metastases)

16. • RAI >30 mci - need isolation
• With in 2–3 days radiation exposure rate reduces to permissible levels
• Then discharged from isolation ward (Should restrict their movements with
young children <13 years and pregnant ladies for next 1-week)

17. NCCN

18. Post therapy
Successful remnant ablation can be defined by an undetectable stimulated
serum Tg, in the absence of interfering Tg antibodies, with or without
confirmatory nuclear or other imaging studies.
An alternative definition in cases in which Tg antibodies are present is the
absence of visible RAI uptake on a subsequent diagnostic RAI scan.
ATA recomm : A posttherapy WBS (with or without SPECT/CT) is
recommended after RAI remnant ablation or treatment, to inform disease
staging and document the RAI avidity of any structural disease.
Can be done from 2 to 12 days

19. LIMITING FACTOR OF 131I DOSAGE
• Radiation dose delivered to bone marrow and blood should not be more than 2 rads
• The retained whole body activity of 131i should be no more than 120 mci at 48 h
• Or 80 mci in patients with lung metastases to avoid potential complication of
pulmonary fibrosis

20. RADIOIODINE REFRACTORY DISEASE
• Occur < 5% of patients with dtc
• More common in older patients
• Large tumour burden
• Poorly differentiated subtypes (hurthle cell histology)
10-year survival
60% - patients with metastatic dtc that retains rai avidity
10% - RAI refractory

21. RADIOIODINE REFRACTORY DISEASE
RAI refractory disease is established when, in patients with appropriate tsh
stimulation:
• the iodine has never concentrated in the metastatic tissue so there is no
uptake outside the thyroid bed
• the tumour tissue has lost the ability to take up iodine despite being
previously rai avid
• iodine can be concentrated in some metastases but not others
• metastatic disease progresses despite significant uptake of rai

22. LOCAL TREATMENT TARGETING RADIOIODINE
REFRACTORY DISEASE
• External beam radiotherapy (EBRT)
• Radiofrequency ablation
• Cryoablation
• Chemo-embolization
• Systemic therapies

23. CERTAIN NORMAL TISSUES TAKE UP RADIOIODINE AND CAN BE
MISCONSTRUED AS METASTASIS
• Salivary glands
• Esophagus ( as a result of swallowing radioactive saliva)
• Thymus
• Breast
• Liver, stomach, colon, bladder

25. ABSOLUTE CONTRAINDICATIONS TO IODINE-131
THERAPY
• Pregnancy
• Lactation
• Elevated urine iodine levels (over 200 μg/l) - should be postponed until
levels return to normal

26. SIDE EFFECTS OF IODINE-131 HIGH DOSE THERAPY

27. THANK YOU