Combined curative radiation therapy alone in (T1) T2-3 rectal adenocarcinoma: a pilot study of 29 patients

A novel rectal applicator for contact radiotherapy with HDR 192Ir sources

PURPOSE

Dose escalation to rectal tumors leads to higher complete response rates and may thereby enable omission of surgery. Important advantages of endoluminal boosting techniques include the possibility to apply a more selective/localized boost than using external beam radiotherapy. A novel brachytherapy (BT) rectal applicator with lateral shielding was designed to be used with a rectoscope for eye-guided positioning to deliver a dose distribution similar to the one of contact x-ray radiotherapy devices, using commonly available high-dose-rate ¹⁹²Ir BT sources.

METHODS AND MATERIALS

A cylindrical multichannel BT applicator with lateral shielding was designed by Monte Carlo modeling, validated experimentally with film dosimetry and compared with results found in the literature for the Papillon 50 (P50) contact x-ray radiotherapy device regarding rectoscope dimensions, radiation beam shape, dose fall-off, and treatment time.

RESULTS

The multichannel applicator designed is able to deliver 30 Gy under 13 min with a 20350 U (5 Ci) source. The use of multiple channels and lateral shielding provide a uniform circular treatment surface with 22 mm in diameter. The resulting dose fall-off is slightly steeper (maximum difference of 5%) than the one generated by the P50 device with the 22 mm applicator.

CONCLUSIONS

A novel multichannel rectal applicator for contact radiotherapy with high-dose-rate ¹⁹²Ir sources that can be integrated with commercially available treatment planning systems was designed to produce a dose distribution similar to the one obtained by the P50 device.

Wait-and-see treatment strategies for rectal cancer patients with clinical complete response after neoadjuvant chemoradiotherapy: a systematic review and meta-analysis

Wait-and-see treatment strategies may benefit rectal cancer patients who achieve a clinical complete response (cCR) after neoadjuvant chemoradiotherapy (NCRT). In this study, we analyzed data from 9 eligible trials to compare the oncologic outcomes of 251 rectal cancer patients achieving a cCR through nonsurgical management approaches with the outcomes of 344 patients achieving a pathologic complete response (pCR) through radical surgery. The two patient groups did not differ in distant metastasis rates or disease-free and overall survival, but the nonsurgical group had a higher risk of 1, 2, 3, and 5-year local recurrence. Hence, we concluded that for rectal cancer patients achieving a cCR after NCRT, a wait-and-see strategy with strict selection criteria, an appropriate follow-up schedule, and salvage treatments achieved outcomes at least as good as radical surgery. Long-term randomized and controlled trials with more uniform inclusion criteria and standardized follow-up schedules will help clarify the risks and benefits of wait-and-see treatment strategies for these patients.

Current treatment of rectal cancer adapted to the individual patient

Preoperative radiochemotherapy and total mesorectal excision surgery is a recommended standard therapy for patients with locally advanced rectal cancer. However, some subgroups of patients benefit more than others from this approach. In order to avoid long-term complications of radiation and chemotherapy, efforts are being made to subdivide T3N0 stage using advanced imaging techniques, and to analyze prognostic factors that help to define subgroup risk patients. Long-course radiochemotherapy has the potential of downsizing the tumor before surgery and may increase the chance of sphincter preservation in some patients. Short-course radiotherapy (SCRT), on the other hand, is a practical schedule that better suits patients with intermediated risk tumors, located far from the anal margin. SCRT is also increasingly being used among patients with disseminated disease, before resection of the rectal tumor. Improvements in radiation technique, such as keeping the irradiation target below S2/S3 junction, and the use of IMRT, can reduce the toxicity associated with radiation, specially long-term small bowel toxicity.

Complete clinical response after preoperative chemoradiation in rectal cancer: is a "wait and see" policy justified?

PURPOSE

A proportion of patients, who receive preoperative chemoradiation for locally advanced (T3, T4, NX) rectal cancer achieve a complete clinical response and a pathologic complete response in the region of 15 to 30 percent. Support is growing in the United Kingdom for the concept of "waiting to see" and not proceeding to radical surgery when a complete clinical response is observed. The purpose of this review was to use a literature search to assess how often complete clinical response is achieved after neoadjuvant chemoradiation, the concordance of this finding with pathologic complete response, and to determine whether it is feasible to observe patients who achieve complete clinical response rather than proceed to surgery.

RESULTS

In total, 218 Phase I/II or retrospective studies and 28 Phase III trials of preoperative radiotherapy or chemoradiation were identified: 96 percent of trials documented the pathologic complete response, but only 38 trials presented data on the achievement of a complete clinical response/partial clinical response. Only five studies were found in which patients with clinically staged T2/T3 tumors were treated with radiotherapy/chemoradiation and did not routinely proceed to surgery and also reported on the long-term outcome of a "wait and see" policy.

DISCUSSION

It remains uncertain whether the degree of response to chemoradiation in terms of complete clinical response or pathologic complete response is a useful clinical end point. Studies that include T3 rectal cancer are associated with high local recurrence rates after nonsurgical treatment. Few studies report long-term outcome after achievement of a complete clinical response.

CONCLUSIONS

The end point of complete clinical response is inconsistently defined and seems insufficiently robust with only partial concordance with pathologic complete response. The rationale of a "wait and see" policy when complete clinical response status is achieved relies on retrospective observations, which are currently insufficient to support this policy except in patients who are recognized to be unfit for or refuse radical surgery.

Non-operative treatment after neoadjuvant chemoradiotherapy for rectal cancer

The past decade has seen pronounced changes in the treatment of locally advanced rectal cancer. Historically, the standard of care involved surgery followed by adjuvant radiotherapy or chemoradiotherapy. More recently, the emergence of neo-adjuvant chemoradiotherapy has fundamentally changed the management of patients with locally advanced disease. In clinical trials, pathological complete responses of up to 25% have raised the question as to whether surgery can be avoided in a select cohort of patients. A trial of omission of surgery for selected patients with complete response after preoperative chemoradiotherapy has shown favourable long-term results. In this article, we outline emerging factors for achieving pathological complete response, non-operative strategies to date, methods for prediction of response to chemoradiotherapy, and future directions with the addition of MRI as a radiological guide to complete response.

Treatment of T1–T2 rectal tumors by contact therapy and interstitial brachytherapy

BACKGROUND AND PURPOSE

We retrospectively analysed our experience of contact therapy alone and/or combined with interstitial brachytherapy as exclusive treatment of low lying rectal tumours.

PATIENTS AND METHODS

From 1971 to 2001, 124 patients (103 adenocarcinomas, 21 villous tumours) were treated by contact therapy alone or combined with interstitial brachytherapy. All patients were staged according to the Dijon classification. The average size of the lesions was 2.4 cm (max 7 cm), clinical aspect was polypoïd in 75% of the cases, flat in 17%. Sixty four patients received contact therapy in three fractions and 44 patients received four fractions, for an average delivered dose of 95 Gy. Interstitial brachytherapy boost delivered 24 Gy on a reference isodose of 55 cGy/h in 10 patients.

RESULTS

The local control was 83% for T1 and 38% for T2 tumours (p=0.004). For mobile tumours, the local control rate is 76%, significantly higher than for tumours with impaired mobility (55%, P=0.03). Thirty-nine patients experienced a local failure (31%). For patients amenable to surgery, a Miles procedure was performed in 25 patients. Ultimate local control rate is 93% for T1, 69% for T2 (P<0.05), 15 patients failed despite treatment for local recurrence (15%). No significant differences were observed in a comparison of adenocarcinoma and villous tumours according to initial and ultimate local control. The mean disease free survival rate for the whole population is 66 months. The 5-year disease free survival for T1a and T1b is, respectively, 82 and 78%, 40 and 25% for T2a and T2b, respectively. The overall 5-year survival for the whole group is 62.4%. At the end of the treatment, 75% of the patients described a very good sphincter function. No deleterious effect on continence was reported during the follow-up.

CONCLUSIONS

The control rate for T1 rectal cancer treated with contact therapy with or without brachytherapy is comparable to surgical series. The sphincter was preserved in 80% of the patients. Radiotherapy remains an efficient and cheap alternative to surgery, mainly for old and fragile patients, or refusing colostomy. The results of these approaches for tumors larger than 3 cm (T2) are not satisfactory. For patients not amenable to surgery, external beam radiation therapy and/or combined modality with chemoradiation should be discussed to increase the loco-regional control rate. A careful selection of patients based on rectal examination and trans-rectal ultrasound could select more accurately patients amenable to such an approach.

Long-term control of T2-T3 rectal adenocarcinoma with radiotherapy alone

PURPOSE

To analyze the long-term result of patients presenting with T2-T3 rectal adenocarcinoma treated with curative intent by radiotherapy (RT) alone, using a combination of contact RT, external beam RT, and brachytherapy with an iridium implant. Patients were considered unsuitable for surgery because of the presence of severe comorbidity or because they did not consent to surgery and the possibility of a permanent stoma.

METHODS AND MATERIALS

Between 1986 and 1998, 63 patients (56 staged with endorectal ultrasonography) were entered into a pilot study. Patients had to have T2-T3, N0-N1, M0 adenocarcinoma of the middle or lower rectum involving less than two-thirds of the circumference. RT began with contact X-rays (80 Gy in 3 fractions for 21 days), followed by external beam RT (39 Gy in 13 fractions for 17 days) with a concomitant boost (4 Gy in 4 fractions). After a 4-6-week interval, an iridium implant delivered a completion dose of 20 Gy to the tumor. No chemotherapy was given.

RESULTS

The median age of the patients was 72 years. Of the 63 patients, 41 had T2 and 22 had T3 tumors. The mean distance of the tumor from the anal verge was 3.6 cm. All patients completed treatment according to the protocol, except for 7 for whom brachytherapy was not performed. With a median follow-up time of 54 months, the primary local tumor control rate was 63%; after salvage surgery, the ultimate pelvic control was 73% (46 of 63). The 5-year overall survival rate was 64.4%, and for 42 patients aged <80 years, it was 78% with 10 patients alive and well at > or =10 years. No severe Grade 3-4 toxicity was seen. Acute proctitis was seen in most patients but did not require treatment interruption. Late rectal bleeding occurred in 24 patients. Only 1 required blood transfusion. Good anorectal function was maintained in 92% of living patients. The T stage was a strong prognostic factor, with a 5-year overall survival rate of 84% and 53% for T2 and T3 lesions, respectively, in patients <80 years old.

CONCLUSION

This is the first report of long-term local control and survival for ultrasound-staged T2-T3 rectal adenocarcinoma treated by RT alone, showing that high-dose irradiation to a small volume can provide a high therapeutic ratio for such tumors.

Addition of oxaliplatin to continuous fluorouracil, l-folinic acid, and concomitant radiotherapy in rectal cancer: the Lyon R 97-03 phase I trial

PURPOSE

Oxaliplatin could increase the efficacy of fluorouracil (5-FU)/folinic acid chemoradiotherapy in rectal cancer. We tested three dose levels to identify a feasible oxaliplatin dose for combination therapy.

PATIENTS AND METHODS

Between February 1998 and April 2000, we included 17 rectal adenocarcinoma patients in a single-center phase I study. Patients had T4 rectal carcinoma, T1-T3 disease with colostomy refusal, or potentially operable T2/T3 M1 requiring local treatment. Pelvic radiotherapy was 45 Gy over 5 weeks, 1.8 Gy/fraction, with concomitant chemotherapy weeks 1 and 5. Chemotherapy was oxaliplatin 80, 100, or 130 mg/m2 2-hour infusion on day 1 followed by L-folinic acid 100 mg/m2/d intravenous bolus, and 5-FU 350 mg/m2/d continuous infusion on days 1 to 5 (FolfoR1). Six patients refusing surgery received additional contact radiotherapy +/- brachytherapy. Dose escalation proceeded if less than two of six patients had dose-limiting toxicity (DLT) at a given dose-level.

RESULTS

All except two patients completed treatment; patients at level 1 (prolonged grade 1 thrombocytopenia) and level 3 (prolonged cold-related dysesthesia) had no second chemotherapy course. Median follow-up is 14 months (range, 2 to 28 months). One elderly patient at dose level 1 had DLT asthenia, severe diarrhea and vomiting, and more than 10% weight loss. There were no other DLTs and no severe rectitis or gastrointestinal toxicity. There were objective responses at all doses and no progressions. Eight patients underwent radical surgery after chemoradiotherapy. Two had complete pathologic responses.

CONCLUSION

FolfoR1 seems feasible and effective. Dose escalation did not increase toxicity. Although the MTD was not reached in this study, we recommend oxaliplatin 130 mg/m2 for phase II studies because it is the dose determined from studies in metastatic patients with no toxicity when given concurrently with radiation.

Sphincter preservation in rectal cancer. External-beam radiation therapy alone

Surgery with or without adjuvant radiation therapy and chemotherapy is the standard treatment for patients with resectable rectal carcinoma. Many patients, however, are medically unfit or simply refuse surgery that could result in a colostomy. This article reviews the results of external-beam radiation therapy alone for selected patients with rectal carcinoma and its role in preserving anorectal function. For patients with mobile tumors, a 5-year survival and local relapse-free rate of 30% and 25%, respectively, can be expected after external-beam radiation therapy alone, and 60% remain colostomy free. Results of radiation therapy alone in patients with fixed or unresectable tumors are poor. Although more than a third of patients remain colostomy-free, only 5% of patients survive 5 years. In patients with mobile rectal carcinomas that are not amenable to sphincter-preserving surgery, who are unfit medically for radical surgery, or who refuse a colostomy, external-beam radiation therapy offers the reality of sphincter preservation and the possibility of long-term tumor control.

Sphincter preservation in rectal cancer. Endocavitary radiation therapy

Endocavitary radiation therapy (Endo RT) is performed mainly with a contact x-ray tube. Interstitial brachytherapy is a supplementary method to boost the tumor bed. Only strictly selected patients can be treated for cure by Endo RT. More than 1,000 patients have been treated in Europe and North America since 1950. In T1 N0 adenocarcinoma, the primary local control rate is close to 90%. The overall 5-year survival is between 60% and 90% depending on patient selection. Careful follow-up is necessary because the majority of local failures can be salvaged, usually by radical surgery. The main advantages of Endo RT are a fully ambulatory and simple treatment that can be applied even in frail or elderly inoperable patients, a low risk of complications, and an inexpensive treatment. Results show it is possible to perform curative treatment in patients with more advanced rectal carcinoma. With the combination of external-beam radiation therapy and Endo RT in stage T2-3 N0-1 tumors, the primary local control rate is around 70%, and the incidence of severe radiation toxicity is less than 5%. Overall 5-year survival is between 50% and 70%. Endo RT can also be used as an adjuvant treatment after local excision, in the treatment of villous adenomas, and for palliation of advanced inoperable tumors.

Comparative treatment planning between proton and X-ray therapy in locally advanced rectal cancer

BACKGROUND AND PURPOSE

Conformal treatment planning with megavoltage X-rays and protons for medically inoperable patients with a large rectal cancer has been studied in an attempt to determine if there are advantages of using protons instead of X-rays.

MATERIAL AND METHODS

Three dose plans were made for each of the six patients: one proton plan, including three beams covering the primary tumour and adjacent lymph nodes and three boost beams covering the primary tumour: one X-ray plan, eight beams including a boost with four beams and one mixed plan with four X-ray beams and a boost with three proton beams. A three dimensional treatment-planning systems, TMS, was used. The evaluation of the different plans was made by applying the biological models TCP and NTCP on the dose distributions in terms of dose-volume histograms.

RESULTS

The comparison shows advantages of using protons instead of X-rays for all six patients, but in three of them, the advantage is only marginal. The dose-limiting organ at risk is the small bowel, but the proton plan and the mixed plan also spare the bladder and the femoral heads better. At 5% NTCP in any risk organ, the calculated mean TCP value for the six patients is increased by 14%-units with the proton plan and 8%-units with the mixed plan compared to X-rays only.

CONCLUSIONS

Proton beam therapy has potential advantages when treating medically inoperable patients with a large rectal cancer over conventional X-ray therapy. Since the benefits are comparatively small, although clinically worthwhile, large randomised studies are needed.