Para-aortic lymph node radiation in advanced cervical cancer

Definition and validation of a reference target volume in early stage node-positive cervical carcinoma, based on lymphangiograms and CT-scans

PURPOSE

To establish a reference planning target volume for postoperative radiotherapy in stage Ib and IIa N+ cervical carcinoma, based on 47 lymphangiograms and 15 CT-scans.

METHODS

Radiation oncologists (n=17) from all radiotherapy institutes in The Netherlands were asked to define the clinical target volume (CTV) and planning target volume (PTV), and to delineate (on simulation films) the radiotherapy treatment portals following a radical hysterectomy with lymph node dissection for an early stage cervical carcinoma with positive iliac lymph nodes. A reference PTV was defined by using 47 normal lymphangiograms and CT-data of the pelvis from 15 patients who underwent surgery for cervical carcinoma. The simulation films were digitized and evaluated for adequacy in covering the PTV, previously individually determined by the radiation oncologists. Subsequently, the simulation films were also evaluated for adequacy in covering the reference PTV.

RESULTS

Large variations were observed in the portals used and in treatment techniques. From the digitized films, it appeared that in 50% of the cases the defined PTV was not covered adequately. Furthermore, 71% of the treatment plans would not cover the lateral borders of the reference PTV sufficiently.

CONCLUSIONS

There appears to be no consensus on the target volumes to be irradiated in postoperative radiotherapy of early stage cervical carcinoma. When a PTV defined on the basis of lymphangiograms and CT-data is taken as a reference, 71% of the treatment plans would not cover this PTV adequately. These findings indicate the need for a consensus in the design of standardized treatment volumes.

Extended field irradiation for carcinoma of the uterine cervix with positive periaortic nodes

Forty-three patients were treated with extended field irradiation for periaortic metastasis from carcinoma of the uterine cervix (FIGO stages IB-IV). Twelve patients (28%) remained continuously free of disease to the time of analysis or death from intercurrent disease, 20 (46%) had persistent cancer within the pelvis, 11 (26%) had persistent periaortic disease, and 23 (53%) developed distant metastasis. The actuarial 5-year survival rate was 32%. The results correlated well with the periaortic tumor burden at the time of irradiation. None of 19 patients (0%) with microscopic or small (less than 2 cm) periaortic disease had periaortic failures, compared to 29% (4/14) of those with moderate-sized (2-5 cm) disease and 70% (7/10) of those with massive (greater than 5 cm) periaortic metastasis. Similarly, the 5-year survival rates were 50% (6/12) with microscopic disease, 33% (2/6) with small gross disease, 23% (3/13) with moderate-sized disease, and 0% (0/10) with massive periaortic metastases. Only 10% (1/10) of patients whose tumor extended to the L1-2 level survived 5 years, compared with 31% (9/29) of those whose disease extended no higher than the L3-4 level. The periaortic failure rates correlated to some extent with the dose delivered through extended fields, although the difference was not statistically significant. Only 8% (1/13) of those who had undergone extraperitoneal lymphadenectomies developed small bowel complications, compared with 25% (7/29) of those who had had transperitoneal lymphadenectomies. The incidence of small bowel obstruction was 8% (1/13) following periaortic doses of 4000-4500 cGy, 10% (1/10) after 5000 cGy, and 32% (6/19) after approximately 5500 cGy. From this, we concluded that the subset of patients who would benefit most from extended field irradiation are those in whom the residual disease in the periaortic area measures less than 2 cm in size at the time of treatment, whose disease extends no higher than L3, and whose cancer within the pelvis has a reasonable chance of control with standard radiation therapy techniques.

Three-dimensional treatment planning for para-aortic node irradiation in patients with cervical cancer

Three-dimensional treatment planning has been used by four cooperating centers to prepare and analyze multiple treatment plans on two cervix cancer patients. One patient had biopsy-proven and CT-demonstrable metastasis to the para-aortic nodes, while the other was at high risk for metastatic involvement of para-aortic nodes. Volume dose distributions were analyzed, and an attempt was made to define the role of 3-D treatment planning to the para-aortic region, where moderate to high doses (50-66 Gy) are required to sterilize microscopic and gross metastasis. Plans were prepared using the 3-D capabilities for tailoring fields to the target volumes, but using standard field arrangements (3-D standard), and with full utilization of the 3-D capabilities (3-D unconstrained). In some but not all 3-D unconstrained plans, higher doses were delivered to the large nodal volume and to the volume containing gross nodal disease than in plans analyzed but not prepared with full 3-D capability (3-D standard). The small bowel was the major dose limiting organ. Its tolerance would have been exceeded in all plans which prescribed 66 Gy to the gross nodal mass, although some reduction in small bowel near-maximum dose was achieved in the 3-D unconstrained plans. All plans were able to limit doses to other normal organs to tolerance levels or less, with significant reductions seen in doses to spinal cord, kidneys, and large bowel in the 3-D unconstrained plans, as compared to the 3-D standard plans. A high probability of small bowel injury was detected in one of four 3-D standard plans prescribed to receive 50 Gy to the large para-aortic nodal volume; the small bowel dose was reduced to an acceptable level in the corresponding 3-D unconstrained plan. An optimum beam energy for treating this site was not identified, with plans using 4, 6, 10, 15, 18, and 25 MV photons all being equally acceptable. Attempts to deliver moderate or high doses (50-66 Gy) to this region should be made only after careful analysis of the plan with techniques similar to those employed in this study.

Extended field irradiation in the treatment of patients with cervical carcinoma involving biopsy proven para-aortic nodes

Between November 1974 and November 1979, 15 patients with cervical carcinoma were treated with extended field irradiation for biopsy proven para-aortic lymph node (PALN) metastases. Treatment consisted of pelvic and para-aortic irradiation at a daily dose of 180 to 200 rad per day, delivering 4000 to 6000 rad to the pelvis and 4000 to 5000 rad to the para-aortic nodes. One or two intracavitary insertions each delivered an additional 2000 to 3500 rad to point A. The three year actual disease free survival for the 12 patients with Stage I and II disease was 50%. All six survivors remain alive without evidence of disease for 41 to 93 months, with a mean and median follow-up of 65 months. All patients dying of disease did so within 26 months, all but one dying within one year. All patients with Stage III and IV are dead of disease. Pelvic disease was controlled in 11 of 12 patients with Stage I or II disease, and in one of the three patients with Stage III and IV disease. There was no clinical indication of failure in the PALN in any patient. Nine patients failed with disseminated disease. Three of 15 patients (20%) suffered serious treatment-related complications. Two of these were attributed to the pelvic irradiation, with one patient requiring a colostomy. Thus, complications resulting from the extended field irradiation were seen in only one patient (6.7%). There was no treatment related mortality. Extended field irradiation can lead to a 50% survival in patients with Stage I and II cervical carcinoma and PALN metastases, a survival comparable to that reported in patients with involved pelvic nodes.

The use of para-aortic radiation therapy based on lymphangiogram interpretation in uterine cervical carcinoma

From January, 1965, to June, 1979, 79 nonrandomized patients with carcinoma of the uterine cervix had a bipedal lymphangiogram (LAG) prior to radiotherapy at the Stanford University Medical Center. In 32 patients the LAGs were interpreted as normal. Of the remaining 47 patients, 28 had LAGs interpreted as positive for metastatic involvement of pelvic nodes alone, 11 as positive for pelvic and para-aortic (PA) metastasis, and 8 as positive in PA nodes alone. Five-year survival and freedom from relapse (FFR) were found to be similar for patients with LAGs interpreted as normal or positive in pelvic nodes only (all stages combined). The addition of elective PA irradiation in those patients with positive pelvic nodes alone (median 5000 rad/5 weeks) did not enhance either survival or FFR in this group. The 19 patients with positive PA nodes had significantly worse survival and FFR when compared with the other groups. Survival was not enhanced by the addition of therapeutic PA irradiation (median 5000 rad/5 weeks) and the 7 patients in this group so treated appeared to have a reduced FFR when compared to the 12 untreated patients. Irrespective of the location of nodal abnormality on LAG and regardless of stage, the majority of relapses (16/23) occurred either centrally or at the pelvic sidewalls. It is concluded that the LAG is a good predictor of subsequent relapse and survival, but that the addition of either elective or therapeutic PA radiotherapy based on LAG interpretation does not affect survival of FFR and should, therefore, be considered for investigational or palliative use only.

Carcinoma of the cervix: surgical staging and radiotherapy with 32 MeV betatron

Fifty-six patients with squamous cell carcinoma of the cervix were staged by exploratory laparotomy. Twenty-eight of them received radiotherapy with 32 MeV Betatron and intracavitary radium. Twenty-one patients with Stage IB or IIA had a radical hysterectomy, five had post-operative pelvic irradiation, and two had primary exenteration. An overall 23.2% of patients had metastases in the paraaortic fields. Four patients with paraaortic node disease received extended field irradiation: 4500 rad in 5 weeks to paraaortic nodes. Two of them are alive and disease-free at 5.5 to 6.5 years.