Volumetric modulated arc technique radiotherapy in synchronous locally advanced rectal and very high-risk prostate cancer

Sujata Sarkar; Ritesh Sharma; Roopesh Reddy Yotham; Dipti Kalita

doi:10.4103/jrcr.jrcr_17_21

CASE REPORT

Year : 2022 | Volume : 13 | Issue : 1 | Page : 32-35

Volumetric modulated arc technique radiotherapy in synchronous locally advanced rectal and very high-risk prostate cancer

Sujata Sarkar¹, Ritesh Sharma¹, Roopesh Reddy Yotham¹, Dipti Kalita²
¹ Department of Radiotherapy, Batra Hospital and Medical Research Centre, New Delhi, India
² Department of Pathology, Batra Hospital and Medical Research Centre, New Delhi, India

Date of Submission	24-Jun-2021
Date of Acceptance	18-Jul-2021
Date of Web Publication	03-Sep-2021

Correspondence Address:
Dr. Sujata Sarkar
Department of Radiotherapy, Batra Hospital and Medical Research Centre, New Delhi
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jrcr.jrcr_17_21

Abstract

Synchronous rectal and prostate cancer is difficult to manage due to old age, complexity of pelvic anatomy, and high morbidity associated with surgery. There is very limited literature available on detailed nonsurgical management. Even achieving high-dose radiotherapy (>70 Gy) for prostate is challenging due to the proximity of rectum, which itself is a target. Few literatures focus on neoadjuvant radiation, but it causes high morbidity following surgery. Other literatures focus on conventional 2 phase radiation, which either is neoadjuvant followed by surgery or causes high toxicity. With the advancement in radiotherapy techniques, volumetric modulated arc technique (VMAT) promises treatment without prostatectomy, with sphincter preservation, and minimal morbidity. Here, we are presenting a case on synchronous locally advanced rectal and very high-risk prostate cancer, treated with radical VMAT technique. Due to the radical dose given in 4 phases, the patient need not undergo surgery, achieved complete response with no symptoms following 6 months of treatment.

Keywords: Complete response, minimal morbidity, sphincter preservation, volumetric modulated arc technique

How to cite this article:
Sarkar S, Sharma R, Yotham RR, Kalita D. Volumetric modulated arc technique radiotherapy in synchronous locally advanced rectal and very high-risk prostate cancer. J Radiat Cancer Res 2022;13:32-5

How to cite this URL:
Sarkar S, Sharma R, Yotham RR, Kalita D. Volumetric modulated arc technique radiotherapy in synchronous locally advanced rectal and very high-risk prostate cancer. J Radiat Cancer Res [serial online] 2022 [cited 2023 Jun 7];13:32-5. Available from: https://www.journalrcr.org/text.asp?2022/13/1/32/325566

Introduction

Multiple primary malignant neoplasms are categorized as synchronous if interval between them is <6 months and metachronous, if interval is >6 months. Even though synchronous cancer is not frequent (5%–8%), the association between prostate and rectal cancer is one of the most common.^[1]

However, treating both of them simultaneously with radiotherapy, doses required to achieve maximum efficacy and minimum toxicity is main limitation in the literature.

Here, we are presenting a rare case of synchronous symptomatic presentation of adenocarcinoma prostate and rectum with different morphology, treated with radiotherapy using volumetric modulated arc technique (VMAT), showing a complete response.

Case Report

A 65-year-old male presented in September 2020 with complaints of increased urinary frequency and constipation for 1 month. On per rectal examination, there was an ulceroproliferative growth 1 cm from the anal verge, 4 cm in length; prostatomegaly with nodularity in the right lobe. Magnetic resonance imaging pelvis showed enlarged prostate 5.8 cm × 5.2 cm × 4.9 cm, extraprostatic extension [Figure 1]a, mass 5.1 cm × 7.3 cm in rectosigmoid lymph nodal mass 3.9 cm × 4.2 cm along left internal iliac [Figure 1]b. Positron emission tomography-computed tomography showed fluorodeoxyglucose (FDG) avid (SUVmax 11.1) lymph nodal mass in right pararectal region 4.4 cm × 4 cm × 5.9 cm, infiltrating into rectosigmoid. FDG avid (SUVmax 12.4) thickening in the right lateral wall of anorectum, length 4.3 cm [Figure 1]c and [Figure 1]d. FDG avid (SUVmax 2.8) lymph nodal mass in left external iliac. Prostate is enlarged with FDG avid (SUVmax 6.2) lesions.

Figure 1: (a) CEMRI pelvis showing T2 hypointensity and nodularity in prostate parenchyma. (b) CEMRI pelvis (T2 sequence) showing lobulated lymph nodal mass along left internal iliac vessels and lobulated exophytic mass in rectosigmoid. (c) Contrast-enhanced computed tomography showing thickening of anorectum with loss of fat plane between rectum and prostate. (d) Three dimensional positron emission tomography image showing increased fluorodeoxyglucose uptake in anorectum and recto-sigmoid. (e) Photomicrograph showing adenocarcinoma of prostate with perineural invasion, Gleason's score 9 (5 + 4) (H and E, ×40). (f) Photomicrograph showing rectum with infiltrating complex neoplastic glands lined by columnar epithelium having moderately pleomorphic, vesicular to hyperchromatic nuclei (H and E, ×40)

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Prostate 12 core biopsy showed adenocarcinoma prostate, Gleason's score (5 + 4) = 9, Grade 5, perineural invasion present, lymphovascular invasion not identified, and tumor involves all cores [Figure 1]e. Immunohistochemistry (IHC) showed PSA (Prostate specific antigen) and AMACAR (p504s) focal positive, CK20 and CD×2 negative.

Rectal biopsy revealed moderately differentiated adenocarcinoma [Figure 1]f. IHC showed CK7 and PSA negative; CK20, CD×2, beta-catenin positive, and high molecular weight cytokeratin weakly positive in few cells.

Serum PSA >120 ng/ml, free PSA 16.54, CEA(carcinoembryonic antigen) 11.38. The case was diagnosed as synchronous dual primary with very high-risk prostate cancer (T3bN1M0) and T3N2 rectal cancer. The patient underwent laparoscopic colostomy for rectal cancer and bilateral orchiectomy for prostate cancer with tablet bicalutamide.

The patient had received concurrent chemoradiation with 3 cycles 3 weekly CAPOX(Capecitabine with Oxaliplatin), C1 on D1 of radiation in November–December 2020.

Radiotherapy was delivered through 4 phase VMAT technique to 75.6 Gy in 42 fractions [Table 1] and [Figure 2], [Figure 3]. Organs at risk (OAR) were contoured including bowel, bladder, penile bulb, cauda equina, and bilateral femurs [Table 2].

Figure 2: (a) Dose distribution from treatment planning system from Phase 1 to 4 and combined Phase 1, 2, 3 and 4. (b) Dose-volume histogram from combined Phase 1, 2, 3, 4 treatments (PTV45-cyan, PTV54-blue, PTV59.4-brown, PTV75.6-translucent blue), organs at risks (both femur heads-both yellow, cauda equina-pale brown). PTV: Planning target volume

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Figure 3: (a) Contouring guidelines of Phase I (CTV-pink, PTV-cyan). (b) Contouring guidelines of Phase II (CTV-dark green, PTV-blue). (c) Contouring guidelines of Phase III (CTV-pink, PTV-brown). (d) Contouring guidelines of Phase IV (CTV-red, PTV-segment blue). CTV: Clinical target volume, PTV: Planning target volume

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Table 1: Contouring guidelines of four phases of radiotherapy

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Table 2: Organ at risks contoured with dose constraints to be achieved as per literature and doses achieved

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The patient had CTCAE v4.0 (Common Terminology Criteria for Adverse Events,published 2009, updated June 14, 2010) Grade 1 neutropenia, Grade 1 fatigue, Grade 1 dermatitis, Grade 2 enteritis, and Grade 1 cystitis.^[2] CEMRI (Contrast enhanced magnetic resonance imaging) pelvis after 3 months and 6 months showed no abnormality. Serum PSA 0.24, CEA 1.58. The patient has currently mild urinary urgency, on androgen deprivation therapy and is under regular follow-up.

Discussion

Prostate and rectal cancers are the most common pelvic malignancies in male and can present either synchronously or metachronously, more likely metachronously, with prior radiotherapy for prostate cancer being the main proposed link.^[3]

Colonias et al.^[4] described the utilization of intensity-modulated radiation therapy (IMRT) technique to deliver radiation to prostate and rectum to avoid prostatectomy and preserve sphincter function, while limiting toxicity.

Qiu et al.^[5] reported a case series of four patients with synchronous prostate and rectal cancers treated with neoadjuvant chemoradiation to the pelvis to 45–50 Gy with concurrent 5-fluorouracil, followed by cesium-131 brachytherapy boost to prostate to 80–90 Gy. All patients subsequently underwent low anterior resection with diverting loop ileostomy. At 24–53 months follow-up, one patient had hormone-refractory metastatic prostate cancer and another had rising CEA.

VMAT is chosen as it offers highly conformal dose delivery, similar target coverage as IMRT but with better OAR sparing, especially to the rectum and femoral heads.^[6] VMAT achieved all the objectives of radiotherapy and can treat this volume in a single arc, whereas IMRT requires multiple beams targeting multiple treatment volumes to spare OARs. The ability to modulate gantry angle, collimation, and dose rate to treat this complex volume makes VMAT more superior than IMRT.^[7] Studies at ALCC (Andrew Love Cancer Centre, Australia) for prostate and anus cases have indicated that VMAT can achieve comparable and often superior plans to IMRT, especially when more planning target volumes are introduced.^[8] VMAT has shorter treatment delivery time.^[9],[10]

Conclusion

Despite being uncommon, the existence of synchronous prostate and rectal cancer will be a clinical problem that will be encountered more frequently due to the increase in life expectancy, since they still remain two of the most frequent malignancies in the male population. Modern radiation techniques like VMAT can deliver radiation to prostate and rectum with the intent of avoiding prostatectomy and preserving sphincter function, while limiting toxicity.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Wu A, He S, Li J, Liu L, Liu C, Wang Q, et al. Colorectal cancer in cases of multiple primary cancers: Clinical features of 59 cases and point mutation analyses. Oncol Lett 2017;13:4720-6.
2.	Common Terminology Criteria for Adverse Events (CTCAE). Common Terminology Criteria for Adverse Events (CTCAE) v. 4.0; 2009. Available from: http://evs.nci.nih.gov/ftp1/CTCAE/CTCAE_4.03_2010-06-14_QuickReference_5x7.pdf. [Last updated on 2010 Jun 14].
3.	Margel D, Baniel J, Wasserberg N, Bar-Chana M, Yossepowitch O. Radiation therapy for prostate cancer increases the risk of subsequent rectal cancer. Ann Surg 2011;254:947-50.
4.	Colonias A, Farinash L, Miller L, Jones S, Medich DS, Greenberg L, et al. Multidisciplinary treatment of synchronous primary rectal and prostate cancers. Nat Clin Pract Oncol 2005;2:271-4.
5.	Qiu H, Herman JM, Ahuja N, DeWeese TL, Song DY. Neoadjuvant chemoradiation followed by interstitial prostate brachytherapy for synchronous prostate and rectal cancer. Pract Radiat Oncol 2012;2:e77-84.
6.	Crowe SB, Kairn T, Middlebrook N, Hill B, Christie DR, Knight RT, et al. Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy. J Med Radiat Sci 2013;60:131-8.
7.	Elith CA, Dempsey SE, Warren-Forward HM. A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early-stage prostate cancer. J Med Radiat Sci 2013;60:84-92.
8.	Sale C, Moloney P. Dose comparisons for conformal, IMRT and VMAT prostate plans. J Med Imaging Radiat Oncol 2011;55:611-21.
9.	Rana S. Intensity modulated radiation therapy versus volumetric intensity modulated arc therapy. J Med Radiat Sci 2013;60:81-3.
10.	Yoo S, Wu QJ, Lee WR, Yin FF. Radiotherapy treatment plans with RapidArc for prostate cancer involving seminal vesicles and lymph nodes. Int J Radiat Oncol Biol Phys 2010;76:935-42.