Contouring guidelines of ca cervix summarised

1. EBRT CONTOURING GUIDELINES
OF CARCINOMA CERVIX
Presented by- Dr. Prachi Kalra

2. OVERVIEW
• Introduction
• Anatomy
• Staging
• Treatment paradigm
• Treatment planning
• Contouring guidelines
• Dose and dose constraints

3. CARCINOMA CERVIX
• India
2nd most common female malignancy
age standardised incidence and mortality 18.0 & 11.4 per 100000
• World
4th most common female malignancy
age standardised incidence and mortality 13.3 & 7.3 per 100000
GLOBOCAN 2020

4. ANATOMY OF THE PELVIS
Cervix is a fibromuscular organ.
Approximately 4cm in length and
3cm in diameter.

5. BONES OF THE PELVIS
Bones to be identified:
• Lumbar vertebrae
• Sacrum- sacro-iliac joint, sacral hollow
• Coccyx
• Ilium
• Pubis
• Ischium- spine, tuberosity
• Obturator foramen
• Acetabulum
• Femoral head
• Lesser trochanter

6. ANATOMY OF THE PELVIS
Transverse cervical ligament,
also known as cardinal
ligament or mackenrodt
ligament, are paired
structures along with
uterosacral and pubocervical
ligaments, provide support
the pelvic organs of the
female pelvis.

7. MUSCLES OF THE PELVIS
Muscles to be identified
1. Iliacus
2. Psoas major
3. Piriformis
4. Coccygeus
5. Levator ani
6. Obturator internus
7. Sacrospinous ligament
8. Urogenital diaphragm

8. MUSCLES OF THE PELVIS

9. LYMPHATIC DRAINAGE

10. CERVICAL CANCER STAGING FIGO 2018
Bhatla, N, Aoki, D, Sharma, DN, Sankaranarayanan, R. Cancer of the cervix uteri: 2021 update. Int J Gynecol Obstet. 2021; 155(Suppl. 1): 28– 44.

11. INCIDENCE OF LYMPH NODE
INVOLVEMENT
Stage Pelvic nodes Para- aortic nodes
IA <1% 0
IB1 15% 6%
IB2/3 25% 10%
II 30% 15%
III 50% 25%
IV 80% 50%

12. TREATMENT PARADIGMS AND
OUTCOMES IN INDIA
FIGO Stage Treatment option 5 year survival (%)
Stage IA1
Stage IA2 Radical hysterectomy,
Radiotherapy
Stage IB1 Radical hysterectomy,
Radiotherapy
Stage IB2,IIA1 Radical hysterectomy,
Chemoradiation
80.6
Stage IB3,IIA2 Chemoradiation
Stage IIIA,IIIB,IIIC Chemoradiation 66
Stage IVA Chemoradiation,
Palliation
37.1
Stage IVB Palliation <5
83.5
Trachelectomy
Survival rate of cervical cancer from a study conducted in India Balasubramaniam G et al IJMMS 2020

13. PRINCIPLES OF RADIOTHERAPY IN
CERVICAL CANCER
• Both the primary lesion and the potential sites of spread should be evaluated
and treated
• The goal of radiotherapy is to kill tumor cells in the cervix, para-cervical tissue
and regional lymph nodes
• Therapeutic ratio is optimized by careful integration of EBRT and
brachytherapy
• Dose and intensity of treatment is based on disease burden and risk of
treatment complications

14. INDICATIONS OF RADIOTHERAPY
• Stage IB2 TO IVA
• Post operative radiotherapy
➢ Tumor size >4cm
➢ Lymphovascular space invasion
➢ Stromal invasion
• Post operative chemoradiotherapy
➢ Lymph node positivity
➢ Margins positive
➢ Parametrial invasion

15. TECHNIQUES-
2D/CONVENTIONAL RT
Box technique
Superior border-L4-5 junction
inferior border- lower border of
obturator foramen, to be extended
below depending on vaginal
involvement
lateral border- 1.5-2cm lateral to
true pelvis brim
Bilateral portal
Anterior border – vertical line
anterior to pubic symphysis
Posterior border – tangent from S2-
S3 vertebrae

16. LIMITATIONS OF CONVENTIONAL
TECHNIQUES

17. 3D CONFORMAL RADIOTHERAPY VS
VMAT

18. 3D CONFORMAL RADIOTHERAPY VS
IMRT

19. TREATMENT PLANNING
STEPS
1. Patient immobilization
2. Imaging
3. Contouring
4. Inverse planning
5. Plan verification and approval
6. Patient set up
7. Patient treatment

20. PRE SIMULATION
• Routine work up
• Metastatic work up
• Hb >10g/dl
• KFT before administering contrast
• History of allergy to contrast must be taken
• Counsel patient about treatment overview, plan, expected toxicities and
precautions to be taken.
• Bladder filling and rectal protocol must be followed

21. PRE SIMULATION
• A vaginal marker is placed at the lower extent of disease when it extends into vagina to
determine the length of vagina involved
• Or the marker can also be placed at the external os and the lower extent of disease
individually determined based on findings of clinical examinations
• Intravenous contrast is used to outline pelvic blood vessels to be used as surrogates for pelvic
node
• Oral and rectal contrast may be given for delineation of critical structures
• CT scan is obtained from T10-T11 interspace to upper third of femur,
• slice thickness may vary from 3-5 mm depending upon institutional protocol
• These images are transferred to treatment planning system (TPS) and contouring is done

22. BLADDER FILLING
• George et al and Pinkawa et al. recommended a full bladder for treatment of
gynecological malignancies, as it displaces sigmoid colon/small bowel loops
• Empty bladder followed by 300-500ml of water
• Planning CT to be taken after 30-40 minutes
• Similar instructions during treatment for consistency

23. ORGAN AT RISK
OAR contouring:
• OARs to be delineated 2cm superior/inferior to PTV
• Bladder:Whole bladder including bladder neck
• Rectum: From anorectal sphincter to recto-sigmoid junction
• Femoral heads: Both femoral head and neck till lesser trochanter
• Bowel bag: Abdominal contents inside peritoneal cavity. To exclude bone,
muscle and major vessels.
• Bone marrow
Reference- gynaecology SOP byTMH

24. ORGAN AT RISK

25. BONE MARROW CONTOURING
Bone marrow sites in
adults
• Ribs, vertebrae,
sternum, bones of the
pelvis

26. BONE MARROW CONTOURING

27. TARGET VOLUMES

29. CTV COMPONENTS
• Gross tumor volume
• Cervix –entire cervix if not already contoured in GTV
• Uterus –entire uterus
• Parametrium- entire parametrium including ovaries, entire mesorectum if
uterosacral ligament involved
• Vagina- minimal or no vaginal extension: upper half of the vagina
upper vaginal involvement: upper two-thirds of the vagina
extensive vaginal involvement: entire vagina

31. ANATOMICAL BORDERS OF PARAMETRIA
location Anatomic structures
Anteriorly Posterior wall of bladder or posterior
border of external iliac vessel
Posteriorly Uterosacral ligaments and mesorectal
fascia
Laterally Medial edge of internal obturator
muscle/ischial ramus bilaterally
Superiorly Tip of fallopian tube/broad ligament.
Depending on degree of uterus flexion,
this may also form the anterior
boundary of parametrial tissue
Inferiorly Urogenital diaphragm

33. • 20 patients
• All pelvic nodes outlined
• Margins generated around vessels- 3mm,5mm,7mm,10mm&15mm
• Muscle and bone excluded
• 7mm margin with minor adjustments showed 99% coverage of lymph nodes

34. RECOMMENDED MODIFICATION TO
MARGINS
Lymph node group Recommended margins
Common iliac 7mm margin around vessels, extend
posterior and lateral borders to psoas
and vertebral body
External iliac 7 mm margin around vessels, extend
anterior border by additional 10mm
anterolaterally along iliopsoas muscle
to include lateral external iliac nodes
Obturator Join external and internal iliac regions
with 18mm wide strip along pelvic side
wall
Internal iliac 7mm margin around vessels, extend
lateral border to pelvic side wall
Presacral 10mm strip over anterior sacrum

35. CONTOURING PELVIC LYMPH NODES

36. CONTOURING PELVIC LYMPH NODES

37. • The aim of the article was to review the guidelines for CTV delineation published in the
literature and to present the guidelines practiced at their institute.
• This is the first report to provide the complete set of guidelines for delineating both the
CTV primary and CTV nodal in combination.
• Literature reviewed from January 2000 to December 2012 to identify published articles on
guidelines for CTV primary and pelvic lymph node (LN) delineation for carcinoma cervix.

38. CTV NODAL CTV1

39. CTV PRIMARY CTV 2&3

40. PTV FINAL

41. DRR

43. CONSENSUS CTV FOR ADJUVANT POSTOPERATIVE
RADIOTHERAPY
Target site Definition
Common iliac lymph nodes From 7mm below L4-L5 interspace to level of
bifurcation of common iliac arteries into external
and internal iliace arteries
External iliac lymph nodes From level of bifurcation of common iliac artery
into external artery to level of superior aspect of
femoral head where it becomes femoral artery
Internal iliac lymph nodes From level of bifurcation of common iliac artery
into internal artery, along its branches (obturator,
hypogastric) terminating in paravaginal tissues at
level of vaginal cuff
Upper vagina Vaginal cuff and 3cm of vagina inferior to cuff
Parametrial/paravaginal tissue From vaginal cuff to medial edge of internal
obturator muscle/ischial ramus on each side
Presacral lymph nodes Lymph node region anterior to S1and S2 region

44. CONSENSUS CTV FOR ADJUVANT
POSTOPERATIVE RADIOTHERAPY

45. • indications
Indications
Definitive:
in radiologically/histologically positive para aortic L.N
Prophylactic: in patients with high risk of para aortic L.N
involvement:
Positive common iliac nodes

46. PARAORTIC NODAL REGION
DELINEATION
• Contour inferior vena cava and aorta
• Superior extent should be left renal vein
• Inferior extent the level of bifurcation of the aorta
• Expand aorta margin by 10mm anteriorly, posteriorly and medially, and 15mm
laterally
• Expand the IVC margin by 8mm anteriorly and medially, and 6mm posteriorly
and laterally

47. CONTOURING AORTIC LYMPH NODES

48. CONTOURING AORTIC LYMPH NODES

49. PARAORTIC NODAL IRRADIATION
EBRT significantly reduced the rate of para-aortic failure (HR 0.35, 95% CI 0.19-0.64;
p<0.01) and the incidence of other distant metastases (HR 0.69, 95% CI 0.50-0.96;
p<0.05)

50. DOSE PRESCRIPTION IN CA CERVIX
• EBRT – 50 Gy / 25 fractions / 5 weeks followed by brachytherapy
• Dose to point A
• 80-85 Gy in early disease
• 85-90 Gy in locally advanced disease
7 Gy in 3 fractions of HDR ( LDR equivalent of 89 Gy to point A)

51. CONVERSION FROM LDR TO HDR - THE
TOTAL DOSE TO POINT A WAS REDUCED
ON AVERAGE BY A FACTOR
Fractions Multiplying factor
1-3 0.54
4-5 0.58
6-8 0.75

52. DOSE CONSTRAINTS
• PTV D95 >97% of prescribed dose and Dmax <115% of prescribed dose
• D2cc bladder < 90Gy EQD2X
• D2cc rectum < 75 Gy EQD2X
• D2cc sigmoid <75 Gy EQD2X
• Femoral heads Dmax <50Gy
• Bowel V45 <195cm3
EQD2X : equivalent total dose in 2-Gy/day fractions, accounting for both the external beam and
brachytherapy dose

53. CHEMORADIATION
• NCI alert was generated in 1999
• Stating platinum based chemotherapy given concurrently with RT prolongs survival
in locally advanced cancer cervix patients.
• Metanalysis done by JCO,2008
➢ 13 trials were reviewed
➢ Aim- Survival advantage with chemoradiotherapy
➢ 19% relative risk reduction in mortality
➢ 6% absolute survival benefit at 5 years p<0.001
➢ There was a significant survival benefit for both the group of trials that used
platinum-based (HR = 0.83, P = .017) and non–platinum-based (HR = 0.77, P = .009)
chemoradiotherapy

54. THANK YOU

55. IMRT VS 3D CRT STUDIES
Phase III tial of IMRT vs 3DCRT for post operative pelvic RT by Klopp et al, JCO
2018
• 278 patients with cervical receiving adjuvant EBRT
• IMRT significantly reduced acute bowel toxicity
• Diarrhoea 34% vs 52%
• Faecal incontinence 1% vs 9%