Acute anal toxicity after whole pelvic radiotherapy in patients with asymptomatic haemorrhoids: identification of dosimetric and patient factors

Objective:

Patients with asymptomatic haemorrhoids are known to be less tolerant of radiation doses lower than known tolerance doses. In the present study, the authors sought to identify the risk factors of acute haemorrhoid aggravation after whole pelvic radiotherapy (WPRT).

Methods:

The records of 33 patients with cervical, rectal or prostate cancer with asymptomatic haemorrhoids, which were confirmed by colonoscopy before the start of radiotherapy (RT), were reviewed. Acute anal symptoms, such as anal pain and bleeding, were observed up to 1 month after RT completion. Dosimetric and patient factors were analysed, and subgroup analyses were performed.

Results:

The median induction dose for acute anal symptoms was 34.1 Gy (range, 28.8–50.4 Gy). Post-operative treatment intent showed more acute anal toxicity of patient factors (p = 0.04). In subgroup analysis, post-operative treatment intent and concurrent chemoradiotherapy were found to be related to acute anal symptoms (p < 0.01). Of the dosimetric factors, V₁₀ tended to be related to acute anal symptoms (p = 0.08).

Conclusion:

This study indicates that asymptomatic haemorrhoid may deteriorate after low-dose radiation and that patient factors, such as treatment intent and concurrent chemotherapy, probably influence anal toxicity. In patients with asymptomatic haemorrhoids, WPRT requires careful dosimetry and clinical attention.

Advances in knowledge:

The tolerance of anal canal tends to be ignored in patients with pelvic cancer who are undergoing WPRT. However, patients with asymptomatic haemorrhoids may be troubled by low radiation doses, and further studies are required.Radiotherapy (RT) is widely used for cancer treatment along with surgery and chemotherapy.^1–5 In particular, whole pelvic RT (WPRT) plays an important role in the locoregional control of pelvic lesions in cervical, rectal and prostate cancer. Although RT is an effective anticancer treatment, it can induce complications in normal organs. There are a lot of studies about radiation tolerance doses in normal organs.^6–8Intestinal problems are common complications of WPRT, whereas severe complications, such as small bowel perforation, are rare.^9,10 On the other hand, acute anal complications, such as anal pain or bleeding, tend to be ignored because of their lower severities. However, acute anal toxicity is a painful, intractable complication. Although most acute anal problems improve spontaneously after RT completion, they are difficult to resolve during RT and result in complaints from many patients. WPRT is usually administered at doses ≤50 Gy, that is, at doses generally considered safe for the anal canal,¹¹ but when patients have haemorrhoids, RT-induced anal toxicity may become problematic.Haemorrhoids are very common and the incidence of asymptomatic haemorrhoids is high.¹² If a patient has haemorrhoids before RT, in many institutions, an anal block is used empirically. Most clinicians expect anal toxicity in patients with haemorrhoids following RT, but published studies on the topic are rare.In the present study, we sought to identify the risk factors of acute anal toxicity following WPRT in patients with pelvic cancer with asymptomatic haemorrhoids.