This document discusses principles of radiotherapy for gastric carcinoma. It summarizes that post-operative radiotherapy can reduce local recurrence rates after surgery for gastric cancer, although no survival benefit has been proven. Newer radiation techniques like IMRT and VMAT may further reduce doses to organs-at-risk compared to 3D conformal radiotherapy. Pre-operative radiotherapy can also improve resectability in some inoperable cases.

1. Principles of Radiotherpy in
Gastric Carcinoma
Dr Anil Gupta
PGI- Chandigarh

2. Introduction
 95% of gastric cancers are adenocarcinoma
Sites of gastric cancer. AJCC
8th edition
Incidence in upper GI tract

3. Epidemiology

4. Trends in Incidence and Survival rate

5. Treatment approach in Gastric carcinoma
 Surgical excision is mainstay of treatment
 No prospective randomized trial have established optimal surgery
 Gastrectomy with D2 lymph node dissection is the standard treatment for curable
gastric cancer in Japan.
 In Western countries, it is considered that survival benefit from extended lymph
node may be from the effect of stage migration (Will Roger Phenomenon)
 Patients with peritoneal involvement, encasement of blood vessels are considered
unresectable

6. Pattern of failures after surgery
Adenocarcinoma of the stomach: areas of failure in a reoperation series. Int J Radiat
Oncol Biol Phys 1982;8:1,
LOCAL FAILURES DISTANT FAILURES

7. *A critical evaluation of subtotal gastrectomy for the cure of
cancer of the stomach. Ann Surg 1957;134:2
†LL. Gastric cancer—patterns of relapse after surgical resection. Semin Radiat Oncol
2002;12:150–161
‡ Local recurrence of gastric adenocarcinomas after gastrectomy. J Surg Oncol 1981;18:47–
53.,Pathology of carcinoma of the stomach. Arch Surg 1943;46:807symb

8. The median overall survival in the surgery only group was
27 months, as compared with 36 months in the
chemoradiotherapy group
Post
gastrectomy(556)
No adjuvant Rx
(275)
ChemoRT
(281)
5-FU 425 mg/m2 + LCV 20mg/m2D1-D5 f/b 4500 cGy/ 25#/5
weeks, with 5- FU and LCV on the first 4 days and the last 3 days
of RT. After 1 month 2 cycles of 5-FU+ LCV was repeated 4 weekly

9. Zhang et al 1998 IJROPB

11. Relapse after ChemoRT

12. Indications
for Post OP RT
 Stage Ib- IV and M0
 Positive resection margins
for Pre OP RT
 Not technically resectable
definitve treatment
 Medically inoperable- palliative intention

13. Treatment planning

14. Superior margin at level T10/11 including left side of the
diaphragm.
Inferior border at L3/4.(for prox 1/3 or GE jn, at lower
level of L1 or L2).
Left lateral border- include all remaining perigastric
nodes, Antral/distal third lesions, the splenic hilum.
Right lateral border- include the preop location of the 1”
tumor, porta hepatis, whichever extends farthest.
2D Conventional Planning
Position supine
AP/PA parallel opposed fields
Weighted equally or anteriorly more to decrease spinal
cord dose

15. Conformal planning

16. Target Delineation

17. OAR delineation

20. 3 D Conformal RT
Beam arrangements

22. Radiation Dose
 4,500-5,040 cGy produce a reasonably good level of local control for completely resected
@1.8Gy/#
 A report from Mayo clinic had high local control with doses >54Gy
 With hyperfractionated RT to dose of 55Gy with 5FU had infield recurrence of 7.5% and
52% 5- year survival
 Reduced boost field to residual disease to 55-60Gy with multi field technique
 In these cases grade 3-4 GI toxicity is expected
Arcangeli 2002 IJROBP

23. Dose constraints
QUANTEC

24. 3DRT vs IMRT in gastric cancer
 57 pts with gastric or GE junction cancer were treated postoperatively: 26 with 3D
CRT and 31 with IMRT. Concurrent chemotherapy was capecitabine (n=31), 5-
fluorouracil (5-FU) (n=25), or none (n=1).
 The 2-year overall survival rates for 3D CRT versus IMRT were 51% and 65%,
respectively (P=.5).
 4 LC failures occurred in the 3D CRT (15%) & IMRT (13%) patients.
 Grade2 acute gastrointestinal toxicity was found to be similar between 3DCRT &
IMRT pts(61.5% vs 61.2%, respectively) but more treatment breaks were needed (3
vs 0, respectively).

25.  The median serum creatinine from before radiotherapy to most recent creatinine was
unchanged in the IMRT group (0.80 mg/dL) but increased in the 3D CRT group from
0.80 mg/dL to 1.0 mg/dL (P=.02).

 Kidney mean dose was higher in the IMRT versus 3DCRT(13.9 Gy vs 11.1 Gy;P=.05) &
kidney V20 was lower for the IMRT vs 3D CRT group (17.5% vs 22%;P=.17).
 The liver mean dose for IMRT & 3DCRT was 13.6 Gy and 18.6 Gy, respectively (P=.19).
The median liver V30 was 16.1% and 28%, respectively (P<.001).
CONCLUSIONS:
 Adjuvant chemoradiotherapy was well tolerated. IMRT was found to provide sparing
to the liver and possibly renal function
Yuriko et al 2010 cancer

26. IMRT vs VMAT
 12 pts were retrospectively analyzed.
 Three techniques showed similar target dose coverage
 The IMRT and sVMAT plans successfully achieved better target dose conformity, reduced the V20/30,
and mean dose of the left kidney, as well as the V20/30 of the liver, compared with the 3D-CRT plans
 sVMAT technique reduced the V20 of the liver much significantly
 Dmax of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5
and 40.6Gy).
 More Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with
gastric cancer after surgery in the future.
Wang et al 2013

27. Conclusion
 There is high local recurrence even after complete surgical excison
 Post OP RT has reduced local recurrences
 Although there is no benefit in overall survival
 Pre OP RT has improved chances of resectibility